ipaserver: Run custodia setup only once

The custodia setup is executed twice. At first in
ipaserver_setup_custodia and then additionally in ipaserver_setup_ca.

The custodia setup code in ipaserver_setup_ca.py has been adapted to fit
the code in ipaserver_setup_custodia.py.

The extra Setup custodia step in the server roles has been removed
together with ipaserver_setup_custodia.py.