Modify distributed transaction commit flow

[harshit-gangal]

Description

This PR updates the commit flow as per the new design doc on atomic distributed transactions.

• Any failure before a commit decision rollback the transaction.
• Any failure before conclude, records a warning and return an error.
• The user can track the transaction state by issuing show warnings and then extracting transaction ID. Later can issue show transaction status for '<id>' to know the current state of it.

Related Issue(s)

• RFC: Atomic Distributed Transactions #16245

Checklist

• 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

[vitess-bot]

Review Checklist

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[codecov]

Codecov Report

Attention: Patch coverage is 75.32468% with 19 lines in your changes missing coverage. Please review.

Project coverage is 68.63%. Comparing base (7f639d3) to head (6e22f8a).
Report is 14 commits behind head on main.

Files	Patch %	Lines
go/vt/vtgate/tx_conn.go	77.02%	17 Missing ⚠️
go/vt/vtgate/production.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16468      +/-   ##
==========================================
- Coverage   68.66%   68.63%   -0.03%     
==========================================
  Files        1550     1552       +2     
  Lines      199307   199544     +237     
==========================================
+ Hits       136846   136961     +115     
- Misses      62461    62583     +122     

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[GuptaManan100]

Logic LGTM

[GuptaManan100]

Why put this in this file? and then a corresponding function in the other file?

[harshit-gangal]

There are multiple reasons

1. This is an unused function in the production build.
2. Anyone can end up using it if this implementation remains in production code.
3. Simple no-op production code will avoid any incidental calls to it.

[systay]

for my own understanding - could we in theory do the clean up in a background thread and answer the user that their commit has been accepted?

[harshit-gangal]

In theory, yes, but it is better to call conclude now, than using goroutine or transaction resolver to conclude.