Renders 404 in commits controller if no commits are found

What does this MR do?

Whenever we show commits and no commits are found a 404 is going to be rendered. The exception for that is when no path is requested and the format is atom.

Why was this MR needed?

@filipa opened #37620 (closed) reporting a white page is rendered when a wrong path is requested.

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 #37620 (closed)