ActionController::UrlGenerationError for old path redirects

What does this MR do and why?

Contributes to #452061 (closed)

Sentry error: https://new-sentry.gitlab.net/organizations/gitlab/issues/699014

Problem

When project path was changed, then we try to redirect all requests from the old path to the new path.

But it's possible that some parameters of the request are incorrect and the generation of new path URL fails.

As a result, we return a 500 error to the user.

Solution

Add an error handler for this case. If the URL generation is not successful, then display a 404 page.