Deprecate twopc_enable flag and change input type for twopc_abandon_age to time.Duration

[harshit-gangal]

Description

This PR deprecate twopc_enable flag to enable TwoPC.
The twopc_abandonage is still mandatory to be set on VTTablet for TwoPC transactions prepare to work.
twopc_abandonage can take in float (deprecated) and time.Duration as input and default is set to 15 minutes.

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

Deployment Notes

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[codecov]

Codecov Report

Attention: Patch coverage is 97.29730% with 1 line in your changes missing coverage. Please review.

Project coverage is 67.50%. Comparing base (f746c48) to head (8598ce3).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vtexplain/vtexplain_vttablet.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17279      +/-   ##
==========================================
+ Coverage   67.48%   67.50%   +0.02%     
==========================================
  Files        1577     1577              
  Lines      253420   253440      +20     
==========================================
+ Hits       171022   171088      +66     
+ Misses      82398    82352      -46     

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[deepthi]

Are we really determining whether to allow 2PC based on twopc_abandonage? Ideally it should be controlled solely by transaction_mode on vtgate, and vttablets should be able to participate.
My suggestion would be to pick a reasonable default for twopc_abandonage and use that. Also we should be changing that to a Duration field instead of float which I assume is being interpreted as seconds.

[GuptaManan100]

I agree with Deepthi. There is no reason to say explicitly whether twopc is enabled or not. If the transaction mode is twopc then we run it, otherwise not.

[harshit-gangal]

For first part - I am aligned with it. Just did not do it in one go.

Changing from seconds to Duration, this would mean a breaking change otherwise would have to add a new flag.

[deepthi]

there's some prior art on how to change this over 2 releases without changing the flag name. you should be able to find the relevant PRs in GH history.

[harshit-gangal]

done dfcd94c

[systay]

still looks good