[kube-prometheus-stack] certmanager use my custom CA

[jcpunk]

Is your feature request related to a problem ?

I'd like to have the prometheus-operator use my custom CA generated by cert-manager.

Describe the solution you'd like.

A setting in values.yaml where I can point to an existing ClusterIssuer.

Describe alternatives you've considered.

Manually rebuilding the certs.

Additional context.

No response