desktop: avoid loading to-be-recovered documents when recovery is disabled

Change-Id: I5c8a117df53e0c7efd1e82ec6e56080c8fd42345
Reviewed-on: https://gerrit.libreoffice.org/13438
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>