Use a friendlier error message when wiki repository is broken

What does this MR do and why?

Related to: Wiki::CouldNotCreateWikiError: Wiki::CouldNotCr... (#396889 - closed)

⚠ This does not fix the root cause of the current problem where a broken wiki repository makes a project almost unusable, instead it avoid breaking the project overview and bring a more friendly error message to users.

Screenshots or screen recordings

Current behavior	New behavior
Screen_Recording_2023-04-11_at_16.26.39

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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