WIP: Only check migration if really needed

What does this MR do?

Only check migration if really needed.

Then pass FAKE_APPLICATION_SETTINGS_IF_NEED_MIGRATION='true'

Why was this MR needed?

A quick attempt to see if this could address gitlab-com/database#96 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist

What are the relevant issue numbers?

See gitlab-com/database#96 (closed)