Unmask neutron-l2gateway-agent service explicitly

unmask parameter in service.running command  doesn't
work properly if service is running.
https://github.com/saltstack/salt/issues/46014

Related-Prod: PROD-23516
Change-Id: Id2d424d868b76d1283503e7df289c2ea856fc88c
diff --git a/neutron/agents/_l2gw.sls b/neutron/agents/_l2gw.sls
index 4a0d70f..a9a28f9 100644
--- a/neutron/agents/_l2gw.sls
+++ b/neutron/agents/_l2gw.sls
@@ -30,6 +30,13 @@
     - pkg: l2gw_agent_packages
 {%- endif %}
 
+# TODO: remove once https://github.com/saltstack/salt/issues/46014 fixed
+l2gw_agent__service_unmask:
+  service.unmasked:
+  - name: neutron-l2gateway-agent
+  - require_in:
+    - service: neutron-l2gateway-agent
+
 neutron-l2gateway-agent:
   service.running:
   - enable: true