Remove Repository#path memoization

What does this MR do?

Removes memoization from Gitlab::Git::Repository#path. This causes some 'disk access violations' that I had to fix.

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Why was this MR needed?

We don't want any (non-test) code to rely on Repository#path. This memoization was fooling our checks that detect path access.

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Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• Conform by the database guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

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