Make dns_domain value configurable

Test test_dns_domain_and_name uses a hardcoded dns_domain value, which
corresponds with the value configured in neutron repository.
This value could change and/or it can be different in other CI jobs.
Due to that, with this patch the dns_domain value becomes configurable.

Change-Id: Ib35b2ecd3a7350f5b744e5e063cfa25b1ecd4806
3 files changed