Use gitaly 0.96.2

What does this MR do?

Bumps the Gitaly version to 0.96.2. Compared to 0.96.1, this adds:

• more gitaly-ruby logging
• gitaly-ruby health checks and automatic restarts

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

There is an increase of incidents on gitlab.com where gitaly-ruby processes get stuck and return ResourceExhausted on all requests. The only way to fix this we know is to restart the gitaly-ruby process. This change automates that restarting.

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
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

gitlab-com/migration#373 (closed)