Add high-cardinality metrics values to KEDA chart

[aliaqel-stripe]

Provide a description of what has been changed

This adds operator.enableHighCardinalityMetrics and metricsServer.enableHighCardinalityMetrics to the KEDA Helm chart.

Both values default to true, matching KEDA core, and wire the --enable-high-cardinality-metrics flag through to the operator and metrics adapter deployments so users can disable the high-cardinality histogram metrics from Helm.

Relates to kedacore/keda#7751

Checklist

• I have verified that my change is according to the deprecations & breaking changes policy
• Commits are signed with Developer Certificate of Origin (DCO - learn more)
• README is updated with new configuration values (if applicable) learn more
• A PR is opened to update KEDA core (repo) (if applicable, ie. when deployment manifests are modified)

Fixes #