ipareplica: Make ipaserver_enable_ipa module working for ipareplica role

The ipareplica role is reusing the ipaserver_enable_ipa module. This module
needed some extensions on the server to enable the delayed services and
also to dump DNS configuration (see commit a1287265).
For replica it is not needed to dump the DNS configuration, therefore it is
simply possible to set detup_dns to no to make this module also working
for ipareplica.