Rescue API calls for filtered merge request searches when response can't be returned

Problem to Solve

In #232999 (closed) we started rescuing searches that would lead to a 500 error because the result set would take too long to process. However, calls directly to the API are not being rescued and instead still return a 500 error.

Proposal

We should rescue API searches that fail for similar query timeout reasons and provide users with a message letting them know that they'll need to further refine their search.