Remove support for opensuse

We haven't been testing the distro for a while in CI, e.g. in
Tempest, the jobs on opensuse15 haven't been executed for a year
now.
Therefore the patch removes opensuse support from devstack.

Closes-Bug: #2002900
Change-Id: I0f5e4c644e2d14d1b8bb5bc0096d1469febe5fcc
diff --git a/lib/horizon b/lib/horizon
index b2bf7bc..f76f9e5 100644
--- a/lib/horizon
+++ b/lib/horizon
@@ -129,7 +129,7 @@
     if is_ubuntu; then
         disable_apache_site 000-default
         sudo touch $horizon_conf
-    elif is_fedora || is_suse; then
+    elif is_fedora; then
         : # nothing to do
     else
         exit_distro_not_supported "horizon apache configuration"