Draft: Disable advisory locks in db:check-schema CI job

What does this MR do and why?

Disable advisory locks in db:check-schema CI job

This CI job is the slowest job in a tier-3 pipeline now, and its duration has crept up to 60 minutes over the last year. Part of the reason that it is slow now is that for every database migration for 3 databases, Rails takes an advisory lock. Since this CI job is only concerned about migrating the database to check the schema, we should not need to worry about concurrent access issues.

Relates to #555535 (closed)

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