Add per runner job timeout

What does this MR do?

Allows Runner owner, to define maximum timeout that can be set for a job handled by that Runner. If project-level timeout is bigger, then Runner-level timeout takes precedence.

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

Requires EE changes - should be merged together with gitlab-ee!4649.

Why was this MR needed?

Screenshots (if relevant)

Runner edit form

Before:

After:

Project CI/CD settings - Runner's details

Before:

After:

Job page

Before:

After:

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-qa manual pipeline job)

What are the relevant issue numbers?

Closes #43426 (closed)