VDiff: Do not intentionally timeout query, and display diff sample binary columns as hex

[mattlord]

Description

This PR makes 2 meaningful quality of life improvements for VDiff:

1. Don't intentionally time out a VDiff query on the source and target at the vreplication copy phase duration timeout, as we're not in the copy phase for a workflow when performing a VDiff. This unnecessarily forces N VDiff resume cycles when diffing a table takes longer than the timeout (default is 1h). This is made potentially more problematic when the table has a complex PK (e.g. N binary columns) and the diff is done across different database versions as this can result in errant mismatches reported due to different ordering of the results on each side.
2. When reporting samples of mismatched rows, print binary column type values in hex so that the user can cut and paste the value as-is in order to further examine the row in question. We were previously printing binary columns as unicode strings and the value would likely have 1 or more invalid unicode chars (the question mark inside a diamond shape) and you would not have the data you need in order to easily identify the row by its primary key column values.

You can see that the query hint is no longer added using the local examples:

git fetch --all && git checkout vdiff_improvements
make build

cd examples/local

./101_initial_cluster.sh && ./201_customer_tablets.sh && ./202_move_tables.sh

vtctldclient --server=localhost:15999 vdiff create --target-keyspace customer --workflow commerce2customer

❯ grep "Streaming rows for query" /opt/vtdataroot/tmp/* | grep rowstreamer
/opt/vtdataroot/tmp/vttablet.INFO:I1217 01:46:29.875357   10853 rowstreamer.go:353] Streaming rows for query: select order_id, customer_id, sku, price from corder force index (`PRIMARY`) order by order_id
/opt/vtdataroot/tmp/vttablet.INFO:I1217 01:46:29.929999   10853 rowstreamer.go:353] Streaming rows for query: select customer_id, email from customer force index (`PRIMARY`) order by customer_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-014611.9138:I1217 01:46:28.644546    9138 rowstreamer.go:353] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ order_id, customer_id, sku, price from corder force index (`PRIMARY`) order by order_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-014611.9138:I1217 01:46:29.661692    9138 rowstreamer.go:353] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ customer_id, email from customer force index (`PRIMARY`) order by customer_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-014611.9166:I1217 01:46:29.868963    9166 rowstreamer.go:353] Streaming rows for query: select order_id, customer_id, sku, price from corder force index (`PRIMARY`) order by order_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-014611.9166:I1217 01:46:29.925814    9166 rowstreamer.go:353] Streaming rows for query: select customer_id, email from customer force index (`PRIMARY`) order by customer_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-014626.10853:I1217 01:46:29.875357   10853 rowstreamer.go:353] Streaming rows for query: select order_id, customer_id, sku, price from corder force index (`PRIMARY`) order by order_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-014626.10853:I1217 01:46:29.929999   10853 rowstreamer.go:353] Streaming rows for query: select customer_id, email from customer force index (`PRIMARY`) order by customer_id

The log messages that still DO have the MAX_EXECUTION_TIME query hint are the ones for the copy phase of the workflow that we are diffing (as they should).

Versus on main:

❯ grep "Streaming rows for query" /opt/vtdataroot/tmp/* | grep rowstreamer
/opt/vtdataroot/tmp/vttablet.INFO:I1217 01:35:53.199903   94401 rowstreamer.go:350] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ order_id, customer_id, sku, price from corder force index (`PRIMARY`) order by order_id
/opt/vtdataroot/tmp/vttablet.INFO:I1217 01:35:53.261233   94401 rowstreamer.go:350] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ customer_id, email from customer force index (`PRIMARY`) order by customer_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-013533.92675:I1217 01:35:51.930562   92675 rowstreamer.go:350] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ order_id, customer_id, sku, price from corder force index (`PRIMARY`) order by order_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-013533.92675:I1217 01:35:52.951606   92675 rowstreamer.go:350] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ customer_id, email from customer force index (`PRIMARY`) order by customer_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-013533.92735:I1217 01:35:53.191411   92735 rowstreamer.go:350] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ order_id, customer_id, sku, price from corder force index (`PRIMARY`) order by order_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-013533.92735:I1217 01:35:53.256384   92735 rowstreamer.go:350] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ customer_id, email from customer force index (`PRIMARY`) order by customer_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-013548.94401:I1217 01:35:53.199903   94401 rowstreamer.go:350] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ order_id, customer_id, sku, price from corder force index (`PRIMARY`) order by order_id
/opt/vtdataroot/tmp/vttablet.pslord.matt.log.INFO.20251217-013548.94401:I1217 01:35:53.261233   94401 rowstreamer.go:350] Streaming rows for query: select /*+ MAX_EXECUTION_TIME(3600000) */ customer_id, email from customer force index (`PRIMARY`) order by customer_id

Related Issue(s)

• Fixes: Bug Report: VDiff Sample Rows For Binary Columns Are not Usable #19043
• Fixes: Feature Request: Don't add MAX_EXECUTION_TIME query hint to VDiff queries #19040

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

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[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.88%. Comparing base (749fe54) to head (2f7e3d9).
⚠️ Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vttablet/tabletmanager/vdiff/report.go	60.00%	8 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #19044    +/-   ##
========================================
  Coverage   69.88%   69.88%            
========================================
  Files        1610     1610            
  Lines      215431   215679   +248     
========================================
+ Hits       150551   150732   +181     
- Misses      64880    64947    +67     

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📝 Documentation updates detected!

New suggestion: Add changelog entry for VDiff improvements

[nickvanw]

This looks good to me other than a test that I think needs updating. Other questions are around changes that look unrelated.

[nickvanw]

Is this intended to be part of the change - if so, I'm not sure how it's part of VDiff

[mattlord]

This was the linter complaining about it after I merged in origin/main.