feat(rules): remove LonghornVolumeActualSpaceUsedWarning

Since the actual size can be bigger than capacity this alert
is not relevant (cf https://www.bookstack.cn/read/longhorn-1.7.1-en/f6cecc15d752a865.md)

charts/longhorn/templates/prometheus-rules.yaml

@@ -11,17 +11,6 @@ spec:
   groups:
   - name: longhorn.rules
     rules:
-    - alert: LonghornVolumeActualSpaceUsedWarning
-      annotations:
-        description: {{"The actual space used by Longhorn volume {{$labels.volume}} on {{$labels.node}} is at {{$value}}% capacity for more than 5 minutes."}}
-        summary: {{"The actual used space of Longhorn volume is over 90% of the capacity."}}
-      expr: (longhorn_volume_actual_size_bytes / longhorn_volume_capacity_bytes) * 100 > 90
-      for: 5m
-      labels:
-        severity: warning
-        {{- with $.Values.servicemonitor.additionalAlertLabels }}
-          {{- toYaml . | nindent 8 }}
-        {{- end }}
     - alert: LonghornVolumeStatusCritical
       annotations:
         description: {{"Longhorn volume {{$labels.volume}} on {{$labels.node}} is Fault for more than 2 minutes."}}