Helm: apply clusterLabel to k8s ServiceMonitors

[thinkmassive]

What this PR does

Applies metaMonitoring.serviceMonitor.clusterLabel to ServiceMonitors for kube-state-metrics and kubelet-cadvisor. This is consistent with the template used to manage Mimir ServiceMonitors.

Which issue(s) this PR fixes or relates to

Fixes #2084 (follow-up to #2125)

Checklist

• [x] Tests updated
• [ ] ~Documentation added~ (n/a, docs already correct)
• [x] CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[CLAassistant]

All committers have signed the CLA.

[thinkmassive]

Hey @dimitarvdimitrov thanks for the review! It's rebased and changelog is updated.