The smbbrowse backend provides custom server cache for libsmbclient.
The cache is currently shared for different samba contexts. That
doesn't work in some cases probably because of changes that were done
in commit 6c8bc39f. Let's drop the cache completely as the backend
doesn't use it in any way. The libsmbclient library will use its own
cache that is separate for each context.

See: https://bugzilla.redhat.com/show_bug.cgi?id=1891358