When a logged-in user accesses a public share link in the same browser,
the system was incorrectly checking if that user's groups were excluded
from creating link shares. This caused share not found errors for users
in excluded groups, even though public shares should be accessible to anyone
with the link.
The group exclusion setting (`shareapi_allow_links_exclude_groups`) is
intended to restrict share creation, not share access. Public shares
are meant to be anonymous and accessible regardless of the viewer identity
or group membership.
We now check the exclusion for the share creator and not the viewer.
Signed-off-by: nfebe <fenn25.fn@gmail.com>