Tags search does not work with Gitaly pagination

What does this MR do and why?

Contributes to #367667 (closed)

Problem

We apply search after we fetched tags from the repository. The pagination breaks this logic.

Solution

Fall back to default tags fetching.

Screenshots or screen recordings

These are strongly recommended to assist reviewers and reduce the time to merge your change.

Before	After

How to set up and validate locally

1. Enable feature flag

   Feature.enable(:tag_list_keyset_pagination)

2. Visit http://127.0.0.1:3000/api/v4/projects/8/repository/tags?pagination=keyset&search=4.0.0
3. You should see the result
4. Switch to master branch
5. Visit http://127.0.0.1:3000/api/v4/projects/8/repository/tags?pagination=keyset&search=4.0.0
6. You should see an empty list (it's a bug 🐛 )

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.