collab_ui: remove branch menu popover in favor of opening a modal (#12562)

This commit also removes a bunch of dead code.

Fixes #12544

Release Notes:

- Removed branch popover menu - clicking on the branch name in left-hand
corner now always opens a branch modal
f0d979576dPiotr Osiewicz committed on 6/1/2024, 4:40:25 PM· committed by GitHubparentfbcc5cc
3 files changedLine totals unavailable