Minor update that fixes the back button for communities

[mspalti]

Description

When the search option was created for communities that added a new path from which result lists originate. I believe that change happened in DSpace 8? I didn't upgrade our site to 8, so my guess is that a back link to community search results just didn't appear item pages.

It looks like there's a different issue after the improvements to back button logic in #5170. You can see the problem by navigating to a collection search page and selecting an item. The back button will return you to the collection page search result. Then navigate to a community search page and select an item. The back button will return you to the previously viewed collection search result list since that was the last route to be cached. You see the same thing when the home page is the last route in the cache.

It looks like we just need to add "communities" to the regex for previous routes so it will be used and properly cached.

Instructions for Reviewers

List of changes in this PR:

• Updated the "previousRoute" regex to include "communities"

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[lgeggleston]

Thank you for contributing this fix @mspalti! Adding to a project board for reviewers to take a look.