Revert "Tests: Remove DNS configuration from trust tests"
    
    This reverts commit 1d9e1521c59a5b43c2322892ce5cbe8cceff2790.
    The reverted commit message states:
    "Since DNS configuration is no longer needed for running trust tests,
    this method's contents are removed."
    In fact tests can run without DNS configuration only in case if test setup
    has a DNS server with DNSSEC support and there are A records for Windows
    machines and SRV records  Windows AD services and this DNS server is used
    as forwarder by bind. If one of these in not true
    then tests fail when trying to establish trust (ipa trust-add) as --server
    option is not used and ipa can not find the AD machine. If we specify
    --server option and add Windows hosts to /etc/hosts, then trust will be
    established, but then sssd will fail to find the host to talk for getting users
    from AD. So for general case we should setup DNS forwarders prior to
    establishing trust, as stated in
    https://www.freeipa.org/page/Active_Directory_trust_setup
    
    Related to https://pagure.io/freeipa/issue/7889
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>