Subscribe / Edit button options no longer appear on Community / Collection "Search" tab

[tdonohue]

Describe the bug

On https://sandbox.dspace.org, you cannot subscribe or edit a Community or Collection from the "Search" tab. You can only do so from a different Browse tab.

This might be related to #3994, which refactored how these options are displayed.

This bug does NOT affect demo.dspace.org, so it's specific to 9.0

To Reproduce

Steps to reproduce the behavior:

1. Login as an Admin
2. Browse to any Community or Collection. Notice that you do NOT see the "subscribe" and "edit" dropdown menu from the default "Search" tab. This is the bug
3. Click on the "By Title" tab (or any other tab) and these options will appear.

Expected behavior

Edit/Subscribe options should exist on all tabs of the Community/Collection page

Related work

May be related to refactor of menus in #3994

[tdonohue]

@YanaDePauw : I just discovered this bug on our https://sandbox.dspace.org site. At a glance, it appears related to your #3994 PR, as the new dropdown menu is not appearing on Community/Collection pages. Would you have time to give it a look?