Git push requests to the existing repo failed after deprecation of 'sql' failover strategy

After upgrade to GitLab 14.0.0-pre c6e57e5aa5c Praefect DB CPU usage maxed at 100% and git push requests to the existing repositories failed. Thanks to @8bitlife in investigation of this issue in gitlab-org/quality/performance#452 (closed), it was found that the issue was caused by deprecation of sql electors #3574 (closed), !3544 (merged).

The environment used the default sql election strategy, please see gitlab-org/quality/performance#452 (comment 592036260). After the deprecation code was deployed to environment it switched to PerRepositoryElector and it in turn it affected the old repositories usage.

When setting i_understand_my_election_strategy_is_unsupported_and_will_be_removed_without_warning = "true", Praefect DB CPU goes down to normal.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information