Description of problem:
The prometheus operator running in the openshift-user-workload-monitoring namespace will fail to reconcile when a user submits a service monitor that references a secret (or configmap) for the TLS configuration.

Version-Release number of selected component (if applicable):
4.6

How reproducible:
Always

Steps to Reproduce:
1. Enable user workload monitoring
2. Create a configmap for future reference
apiVersion: v1
data:
  ca.crt: test
kind: ConfigMap
metadata:
  name: ca-cert-demo
  namespace: default

3. Create a service monitor referencing the configmap above
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  labels:
    app: demo
  name: demo
  namespace: default
spec:
  endpoints:
  - port: web
    tlsConfig:
      ca:
        configMap:
          key: ca.crt
          name: ca-cert-demo
  selector:
    matchLabels:
      app: demo

Actual results:

The prometheus operator's logs show warnings:
level=warn ts=2020-08-18T14:06:02.864503096Z caller=operator.go:1829 component=prometheusoperator msg="skipping servicemonitor" error="SecretOrConfigMap can not specify both Secret and ConfigMap" servicemonitor=default/demo namespace=openshift-user-workload-monitoring prometheus=user-workload

Expected results:

No warbubg in the logs. The prometheus operator processes the service monitor successfully.

Additional info: