Update NGFHigh5xxRate alert to exclude forms-api hosts from error rate calculation

Author: jb3

kubernetes/namespaces/loki/alert_rules.yml

@@ -192,7 +192,7 @@ data:
               (
                 sum by (host) (
                   rate(
-                    {namespace="nginx-gateway", app_container="/nginx"}
+                    {namespace="nginx-gateway", app_container="/nginx", host!~"forms-api.*"}
                     | json
                     | __error__ = ""
                     | status >= 500
@@ -202,7 +202,7 @@ data:
                 /
                 sum by (host) (
                   rate(
-                    {namespace="nginx-gateway", app_container="/nginx"}
+                    {namespace="nginx-gateway", app_container="/nginx", host!~"forms-api.*"}
                     | json
                     | __error__ = ""
                     [5m]