GTID and other go/mysql and vstreamer optimizations

[shlomi-noach]

Description

This is an extract from #17628. While working on #17628 we:

• Improved parsing of GTID events
• Found speed and memory improvements around GTID computation and otherwise specifically in vstreamer.

In this PR we have the following improvements:

go/mysql

• Parse PREVIOUS_GTIDS event
• Extract last_committed (aka commit parent) and sequence_number from GTID event
• Optimize timestamp format
• In-place add GTID and union GTID -- this saves a lot of memory allocation and gc collection

vstreamer.go

• Handle PREVIOUS_GTIDS event
• Use in-place addition of GTID (there's no need for the streamer's GTIDSet to be immutable and this is wasteful)
• Optimize formatting of GTID (just once for the GTID events group as opposed to every event)
• Optimize time.Now() generation (same timestamp for GTID group)
• Apply SequenceNumber and LastCommitted to all events.

Related Issue(s)

#17628

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

Deployment Notes

[vitess-bot]

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[codecov]

Codecov Report

❌ Patch coverage is 74.87923% with 52 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.52%. Comparing base (104b755) to head (b8ec791).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
go/mysql/replication/mariadb_gtid.go	12.50%	14 Missing ⚠️
go/mysql/replication/replication_position.go	46.15%	14 Missing ⚠️
go/mysql/replication/mysql56_gtid_set.go	92.63%	7 Missing ⚠️
go/vt/vttablet/tabletserver/vstreamer/vstreamer.go	79.31%	6 Missing ⚠️
go/mysql/binlog_event_filepos.go	33.33%	4 Missing ⚠️
go/mysql/replication/filepos_gtid.go	50.00%	4 Missing ⚠️
go/mysql/replication/mysql56_gtid.go	60.00%	2 Missing ⚠️
go/vt/binlog/binlog_streamer.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #18196      +/-   ##
==========================================
+ Coverage   67.49%   67.52%   +0.02%     
==========================================
  Files        1607     1607              
  Lines      263144   263324     +180     
==========================================
+ Hits       177621   177805     +184     
+ Misses      85523    85519       -4     

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[github-actions]

This PR is being marked as stale because it has been open for 30 days with no activity. To rectify, you may do any of the following:

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• Remove the stale label.
• Add a comment indicating why it is not stale.

If no action is taken within 7 days, this PR will be closed.

[github-actions]

This PR is being marked as stale because it has been open for 30 days with no activity. To rectify, you may do any of the following:

• Push additional commits to the associated branch.
• Remove the stale label.
• Add a comment indicating why it is not stale.

If no action is taken within 7 days, this PR will be closed.