travis: Remove CI integration

Removing Travis CI in favour of Azure Pipelines.

All tests previously tested by Travis are also configured in Azure.

Repos [1] and [2] were used to build Docker images for Travis, thus
they are no longer required for branches master and ipa-4-8.

Branches ipa-4-7 and ipa-4-6 don't have Azure pipelines configured,
so Travis will continue to be used by them.

1 - https://github.com/freeipa/ipa-docker-test-runner
2 - https://github.com/freeipa/freeipa-builder

Related: https://pagure.io/freeipa/issue/7323

Signed-off-by: Armando Neto <abiagion@redhat.com>
Reviewed-By: Francisco Trivino <ftrivino@redhat.com>

ipaplatform/redhat/tasks.py

@@ -188,12 +188,6 @@ class RedHatTaskNamespace(BaseTaskNamespace):
                 "globally, disable it on the specific interfaces in "
                 "sysctl.conf except 'lo' interface.")
 
-        # XXX This is a hack to work around an issue with Travis CI by
-        # skipping IPv6 address test. The Dec 2017 update removed ::1 from
-        # loopback, see https://github.com/travis-ci/travis-ci/issues/8891.
-        if os.environ.get('TRAVIS') == 'true':
-            return
-
         try:
             localhost6 = ipautil.CheckedIPAddress('::1', allow_loopback=True)
             if localhost6.get_matching_interface() is None: