ipaclient_setup_nss: Use proper nosssd_files list

ipaclient_setup_nss is using the nosssd_files dict if sssd is disabled
with no_sssd.

The nosssd_files dict is generated in ipaclient_test and used in
ipaclient_setup_nss. So far ipaclient_setup_nss was using nosssd_files
from ipaclient installer, which was always None.