[Accessibility] Empty (invisible) buttons appear on /community-list

[tdonohue]

Describe the bug
Originally reported in #2055 (comment)

If you use the WAVE browser plugin on the /community-list page, it will report several "Empty button" errors. NOTE: These errors will only be reported for Communities which have displayed "short description" text under the Community name.

These are invisible buttons which have no text or aria-label. They are not seen as errors by all accessibility tools though (e.g. they are not detected by the Deque Axe DevTools browser plugin).

To Reproduce
Steps to reproduce the behavior:

1. Reproducible on the demo site at https://demo.dspace.org/community-list (or with any local site using our demo entities data set)
2. Enable the WAVE browser plugin on the page. You will see a number of "Empty button" Errors reported. (The exact number of errors depends on the number of communities displayed)
   • Click on the "Details" and view only those "Empty Button" errors (deselect everything else)
   • You'll see the errors come from any Community in the list which has a "short description" displayed.

Expected behavior
No errors should occur. It's likely these buttons simply need to have an aria-label or some similar descriptive text, so that they are no longer seen as empty. Alternatively, these buttons could be removed from the page (as they are invisible) if doing so does not impact page behavior.

Related work
Related to #2055, where it was originally reported.