Display full pre-receive and post-receive hook output in GitLab UI

What does this MR do?

Displays the full message from pre-receive and post-receive hooks in GitLab UI

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

Is there a better way to handle the line breaks in the hook output?

Why was this MR needed?

Currently only the first line of output from a pre-receive or post-receive hook is displayed.

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

What are the relevant issue numbers?

Closes #25214 (closed)