L2SS-394: Enable 'next-gen alerting' in Grafana:...

L2SS-394: Enable 'next-gen alerting' in Grafana: https://grafana.com/docs/grafana/latest/alerting/unified-alerting/

docker-compose/grafana/grafana.ini

@@ -966,7 +966,7 @@ enabled = true
 
 [feature_toggles]
 # enable features, separated by spaces
-;enable =
+enable = ngalert
 
 [date_formats]
 # For information on what formatting patterns that are supported https://momentjs.com/docs/#/displaying/