Revert "Install Mirantis theme for Horizon"

This reverts commit 76438e93df141aa608fbd6f2b6e351e8ba6727a8.

Change-Id: I769e254bdb69b620a0cc755b1604d081a73e28e2
diff --git a/classes/cluster/virtual-mcp11-aio/openstack/init.yml b/classes/cluster/virtual-mcp11-aio/openstack/init.yml
index 3ae4807..f6780fb 100755
--- a/classes/cluster/virtual-mcp11-aio/openstack/init.yml
+++ b/classes/cluster/virtual-mcp11-aio/openstack/init.yml
@@ -36,7 +36,6 @@
 - service.cinder.volume.single
 - system.cinder.volume.backend.lvm
 - system.horizon.server.single
-- system.horizon.server.plugin.theme
 - system.bind.server.single
 - system.barbican.server.single
 - service.barbican.server.plugin.simple_crypto