As part of MON-1633, namespace owners should be able to opt out from being monitored by user workload monitoring (for instance they use a dedicated Prometheus instance to monitor their workload). We can configure the UWM prometheus operator to exclude all namespaces with a specific label (e.g. "openshift.io/user-monitoring:'false'").

DoD:

• UWM doesn't pick up service/pod monitors and rules from namespaces labeled with the predefined label.
• When the label is removed (or changed), UWM picks it up automatically.