Set default timeout for deleting many refs

Prior to this change, this RPC had a fast_timeout. This timeout doesn't
set no timeout on Sidekiq. Deleting many refs can take over a couple of
seconds, so a default timeout would be neccesairy.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/49862

lib/gitlab/gitaly_client/ref_service.rb

@@ -166,7 +166,7 @@ module Gitlab
           except_with_prefix: except_with_prefixes.map { |r| encode_binary(r) }
         )
 
-        response = GitalyClient.call(@repository.storage, :ref_service, :delete_refs, request, timeout: GitalyClient.fast_timeout)
+        response = GitalyClient.call(@repository.storage, :ref_service, :delete_refs, request, timeout: GitalyClient.default_timeout)
 
         raise Gitlab::Git::Repository::GitError, response.git_error if response.git_error.present?
       end