reduce severity level to warning (#28939)

Signed-off-by: bergquist <carl.bergquist@gmail.com>

grafana-mixin/alerts/alerts.yaml

 groups:
-- name: GrafanaAlerts
+  - name: GrafanaAlerts
     rules:
       - alert: GrafanaRequestsFailing
         for: 5m
@@ -9,6 +9,6 @@ groups:
           namespace_job_handler_statuscode:http_request_total:rate5m{handler!~"/datasources/proxy/:id.*|/ds/query|/tsdb/query"}
           > 0.5
         labels:
-      severity: 'critical'
+          severity: 'warning'
         annotations:
           message: "'{{ $labels.namespace }}' / '{{ $labels.job }}' / '{{ $labels.handler }}' is experiencing {{ $value | humanize }}% errors"