delete unused flags and handling of deprecated protobuf fields

[deepthi]

Description

• A number of deprecated flags from previous releases have been deleted
• Special handling for deprecated protobuf fields has been deleted

Related Issue(s)

#5960

Checklist

• "Backport me!" label has been added if this change should be backported
• Tests were added or are not required
• Documentation was added or is not required - release notes summary is included, website PR

Deployment Notes

[github-actions]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
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• If a new flag is being introduced, review whether it is really needed. The flag names should be clear and intuitive (as far as possible), and the flag's help should be descriptive.
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Bug fixes

• There should be at least one unit or end-to-end test.
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Non-trivial changes

• There should be some code comments as to why things are implemented the way they are.

New/Existing features

• Should be documented, either by modifying the existing documentation or creating new documentation.
• New features should have a link to a feature request issue or an RFC that documents the use cases, corner cases and test cases.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• vtctl command output order should be stable and awk-able.

[GuptaManan100]

This looks good to me! I wonder if 8 releases are enough to remove a deprecated flag 😆

[GuptaManan100]

TestHelpOutput is failing the end-to-end test, because the output for vttablet --help has changed to not include the deprecated commands

[GuptaManan100]

@deepthi I have pushed a fix for it.

[deepthi]

topo_connection_cache is a valid failure

2022-06-29T14:38:02.0006759Z I0629 14:27:10.354376   15288 vttablet_process.go:152] vttablet error:
2022-06-29T14:38:02.0007321Z flag provided but not defined: -enable-autocommit

I will fix it. I wonder why more tests haven't failed with this error.

[harshit-gangal]

java side changes looks good

[GuptaManan100]

Apparently, we are passing one of these flags in the vtop, so the end-to-end tests suddenly broke there and I traced it back here 🤣 . Anyways, I'll create a PR fixing this there.

[GuptaManan100]

Commenting for completeness, the commit for fixing this on Vtop - planetscale/vitess-operator@a35f74b