server: remove unused objects related to threading
server: remove unused objects related to threading

Threads are not used since 57ae68002f46670552444b11d0789f3dc041b432.

Signed-off-by: Jakub Janků <e6d62f7189d9c45efd907e4f2baf6f535f551138@redhat.com>

GNOME/phodav,GNOME/phodav