Revert: Revert temporary workflow changes made in #10847

[mattlord]

Description

In #10896 we reverted the temporary upgrade/downgrade backup manual workflow changes made in #10847.

This was done because the MySQL 8.0.30 backup fixes were merged into the release-14.0 branch via #10895 and given that "v14 had the fix" (though not in an official release) we should no longer need to pin the MySQL version.

Well... I was mistaken about what we downgraded to in this workflow. I thought we built binaries on the previous release branch, in this case release-14.0, but instead we checkout the latest release tag which is v14.0.1 today.

You can see this here:

vitess/.github/workflows/upgrade_downgrade_test_backups_manual.yml

Lines 24 to 29 in 853d88d

	- name: Set output with latest release branch
	id: output-previous-release-ref
	run: |
	previous_release_ref=$(./tools/get_previous_release.sh ${{github.base_ref}} ${{github.ref}})
	echo $previous_release_ref
	echo "::set-output name=previous_release_ref::${previous_release_ref}"

And here: https://github.com/vitessio/vitess/blob/main/tools/get_previous_release.sh

And you can see an example workflow which fails to perform the backup on the downgraded v14.0.1 binaries here: https://github.com/vitessio/vitess/runs/7642110846?check_suite_focus=true

So in this PR we put the temporary workflow changes back in place and update the comment in the workflow to reflect that these MySQL version pinning changes cannot be removed until either of the following occur:

1. v14.0.2 is released
2. The dev version on main becomes 16.0.0-SNAPSHOT (meaning the v15.0.0 release candidate has been cut)

Related Issue(s)

• Follow-up to: Backups: Support InnoDB Redo Log Location With 8.0.30+ #10847
• Reverts: Revert temporary workflow changes made in #10847 #10896

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

[vitess-bot]

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[deepthi]

Thank you