Make the circuitbreaker configurable at runtime

What does this MR do?

This removes the settings for the Git-storage circuitbreaker out of a configuration file and into the database.

Why was this MR needed?

This is part of https://gitlab.com/gitlab-org/gitlab-ce/issues/37383 to make these properties adjustable at runtime.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Squashed related commits together

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/37383