Enable disk check on containerized installs

According to the docs the disk requirements should be similar to
non-containerized installs.

https://docs.openshift.org/latest/install_config/install/rpm_vs_containerized.html#containerized-storage-requirements

roles/openshift_health_checker/openshift_checks/disk_availability.py

@@ -4,10 +4,9 @@ import os.path
 import tempfile
 
 from openshift_checks import OpenShiftCheck, OpenShiftCheckException, get_var
-from openshift_checks.mixins import NotContainerizedMixin
 
 
-class DiskAvailability(NotContainerizedMixin, OpenShiftCheck):
+class DiskAvailability(OpenShiftCheck):
     """Check that recommended disk space is available before a first-time install."""
 
     name = "disk_availability"

roles/openshift_health_checker/test/disk_availability_test.py

@@ -3,22 +3,19 @@ import pytest
 from openshift_checks.disk_availability import DiskAvailability, OpenShiftCheckException
 
 
-@pytest.mark.parametrize('group_names,is_containerized,is_active', [
-    (['masters'], False, True),
-    # ensure check is skipped on containerized installs
-    (['masters'], True, False),
-    (['nodes'], False, True),
-    (['etcd'], False, True),
-    (['masters', 'nodes'], False, True),
-    (['masters', 'etcd'], False, True),
-    ([], False, False),
-    (['lb'], False, False),
-    (['nfs'], False, False),
+@pytest.mark.parametrize('group_names,is_active', [
+    (['masters'], True),
+    (['nodes'], True),
+    (['etcd'], True),
+    (['masters', 'nodes'], True),
+    (['masters', 'etcd'], True),
+    ([], False),
+    (['lb'], False),
+    (['nfs'], False),
 ])
-def test_is_active(group_names, is_containerized, is_active):
+def test_is_active(group_names, is_active):
     task_vars = dict(
         group_names=group_names,
-        openshift=dict(common=dict(is_containerized=is_containerized)),
     )
     assert DiskAvailability.is_active(task_vars=task_vars) == is_active