[OVN] Do not check L3 agents state with ML2/OVN

With [1], the ML2/OVN L3 plugin will have the "ha" API extension
enabled. The OVN L3 plugin does not have L3 agents; this check
should be skipped.

[1]https://review.opendev.org/c/openstack/neutron/+/910889

Related-Bug: #2020823
Change-Id: I09c12ba36b007d4f6fdd3723974ecfe9e4466b72
diff --git a/neutron_tempest_plugin/scenario/base.py b/neutron_tempest_plugin/scenario/base.py
index 9d53f79..021b3b7 100644
--- a/neutron_tempest_plugin/scenario/base.py
+++ b/neutron_tempest_plugin/scenario/base.py
@@ -236,7 +236,7 @@
     @classmethod
     def _wait_for_router_ha_active(cls, router_id):
         router = cls.os_admin.network_client.show_router(router_id)['router']
-        if not router.get('ha'):
+        if not router.get('ha') or cls.is_driver_ovn:
             return
 
         def _router_active_on_l3_agent():