Testimonial view shows an incorrect vendor - Database issue

[BradHN1]

Describe the bug
Mike Roy reports that on Energy Naviagators site in the Testimonial List view (not individual testimonial page) a vendor is shown which has nothing to do with the testimonial or related action.

In the Admin portal, I can see there is no vendor selected in this testimonial:

However in Django Admin I can see that there is a vendor selected:

Note that I have fixed the individual instances of testimonails pointing to that vendor in the Django Admin. But it is happening on other communities., for example Cooler Concord:

Expected behavior
Note there are at least 2 problems to fix:

1. an incorrect vendor gets linked to a Testimonial when none was specified;
2. The Admin portal doesn't show the vendor on the Edit Testimonial page.
   (this could be because the Vendor is not from the community)

The expected behavior is that no bogus vendors get ltagged in Tesmonials
And any testimonial vendor shown in Django Admin shows up also in the Edit Testimonial page.