Use Gitlab::Git::Finders::RefsFinder in repository_branch_names_resolver.rb

Context

We need to use Gitlab::Git::Finders::RefsFinder in repository_branch_names_resolver.rb.

The repository_branch_names_resolver.rb resolver uses Repositories::BranchNamesFinder which relies on Redis SSCAN to search repository branches by name. SSCAN mechanism uses glob-style patterns.

Since we are working on stopping the storage of branch_names in Redis, we need to replace BranchNamesFinder in RepositoryBranchNamesResolver with RefsFinder.

This will also contribute to Swap searching of branches/tags over to Gitaly (&11057).