Deleting proxies does not delete (potentially wrong) thumbnails created from those proxies
@jeff
Submitted by Jeff F.T. Assigned to Alex Băluț @aleb
Description
Pitivi can generate "wrong" thumbnails for proxies as seen in T7607.
When I right-click a clip and manually tell it to "delete the proxy", I expect Pitivi to purge the thumbnail along with the proxy, and to reattempt thumbnailing from the original through gnome's thumbnailer like it did before.