Add prometheus rules to cloudnative-pg chart

[maxpain]

Hello. I use the cloud-native-pg chart to deploy the CNPG operator, and all my Cluster, ScheduledBackup, and Pooler resources are managed by the Flux CD repository (GitOps), so I don't want to use the cluster chart.

Would you mind adding Prometheus rules as in the cluster chart to cloud-native-pg? Currently, I use https://raw.githubusercontent.com/cloudnative-pg/cloudnative-pg/refs/tags/v1.24.0/docs/src/samples/monitoring/prometheusrule.yaml, but there are fewer rules than in the cluster chart.