cms/openstack: Fix port group reference in acls.

The current code refer to a portgroup named $pg_pg... which is
not correct.

Signed-off-by: Frode Nordahl <frode.nordahl@canonical.com>

ovn-tester/cms/openstack/openstack.py

@@ -639,8 +639,8 @@ def _create_default_security_group(self) -> PortGroup:
             f"inport == @{pg_name} && ip6",
         ]
         out_rules = [
-            f"outport == @{pg_name} && ip4 && ip4.src == $pg_{pg_name}_ip4",
-            f"outport == @{pg_name} && ip6 && ip6.src == $pg_{pg_name}_ip6",
+            f"outport == @{pg_name} && ip4 && ip4.src == ${pg_name}_ip4",
+            f"outport == @{pg_name} && ip6 && ip6.src == ${pg_name}_ip6",
         ]
 
         for rule in in_rules: