Monitoring operator is degraded with alertmanager-main-x pods in CrashLoopBackOff state due to missing configuration in alertmanager secret in RHOCP4

Issue

• Monitoring operator is degraded with below error:

  lastTransitionTime: '2022-03-09T13:56:30Z'
  message: 'Failed to rollout the stack. Error: updating alertmanager: waiting for
    Alertmanager object changes failed: waiting for Alertmanager openshift-monitoring/main:
    expected 3 replicas, got 0 updated replicas'
  reason: UpdatingAlertmanagerFailed
  status: 'True'
  type: Degraded
  
  

• alertmanager-main-x pods are in CrashLoopBackOff state as below:

NAME                                           READY   STATUS             RESTARTS      AGE
alertmanager-main-0                            4/5     CrashLoopBackOff   6 (66s ago)   7m22s
alertmanager-main-1                            4/5     CrashLoopBackOff   6 (62s ago)   7m14s
alertmanager-main-2                            4/5     CrashLoopBackOff   6 (57s ago)   7m8s

• alertmanager-main-x pod container alertmanager reporting below error log:

2022-03-09T18:40:16.371281276Z level=error ts=2022-03-09T18:40:16.370Z caller=coordinator.go:118 component=configuration msg="Loading configuration file failed" file=/etc/alertmanager/config/alertmanager.yaml err="address smtp.<xxxxx>.com: missing port in address"