https://gitlab.com/gitlab-org/gitlab/-/merge_requests/117453 dropped
`initRefSwitcher`, but there was still one stale call left to
`Project.initRefSwitcher()` that caused an undefined method error
after merging. This error didn't actually prevent merges from going
through.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/407833

Changelog: fixed