Add FF disable setting last_used_at on SSH access [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

This allows circumventing setting the last_used_at flag when accessing repositories through git-ssh.

This is a band aid for gitlab-com/gl-infra/scalability#889 (moved)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done