chore: use PodMonitoring in charts instead (#12571)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **Refactor**
  - Updated monitoring configuration to use a different resource type with simplified naming and label selectors for Kubernetes manifests.
- **Chores**
  - Removed Google Cloud Platform–specific monitoring configuration files from multiple components.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.github/helm/affine/templates/monitoring.yaml

@@ -0,0 +1,13 @@
+{{- if eq .Values.global.deployment.platform "gcp" -}}
+apiVersion: monitoring.googleapis.com/v1
+kind: PodMonitoring
+metadata:
+  name: "{{ .Release.Name }}-monitoring"
+spec:
+  selector:
+    matchLabels:
+      app.kubernetes.io/instance: {{ .Release.Name }}
+  endpoints:
+    - port: 9464
+      interval: 30s
+{{- end }}