Description of problem:
Tested with PR
https://github.com/openshift/cluster-monitoring-operator/pull/1567
lauched cluster-bot cluster:
launch 4.11-ci,openshift/cluster-monitoring-operator#1567

set "repeatInterval: 12hours" in AlertmanagerConfig which value is wrong, it reported error "repeatInterval 5m does not match required regex: ^(([0-9]+)y)?(([0-9]+)w)?(([0-9]+)d)?(([0-9]+)h)?(([0-9]+)m)?(([0-9]+)s)?(([0-9]+)ms)?$", but it is actually "repeatInterval: 12hours"

steps:
# oc new-project test;
# oc -n test create -f - << EOF
apiVersion: monitoring.coreos.com/v1alpha1
kind: AlertmanagerConfig
metadata:
  name: invalid-test-config
  labels:
    alertmanagerConfig: example
spec:
  route:
    groupBy: ['job']
    groupWait: 30s
    groupInterval: 5m
    repeatInterval: 12hours
    receiver: webhook
  receivers:
  - name: webhook
    webhookConfigs:
    - url: 'https://example.com'
      sendResolved: true
      httpConfig:
        followRedirects: true
  - name: wechat-example
    wechatConfigs:
    - apiURL: https://wechatserver:8080/
      corpID: wechat-corpid
      apiSecret:
        name: wechat-config
        key: apiSecret
EOF

The  "alertmanagerconfigs" is invalid: : repeatInterval 5m does not match required regex: ^(([0-9]+)y)?(([0-9]+)w)?(([0-9]+)d)?(([0-9]+)h)?(([0-9]+)m)?(([0-9]+)s)?(([0-9]+)ms)?$

# oc explain AlertmanagerConfig.spec.route.repeatInterval
KIND:     AlertmanagerConfig
VERSION:  monitoring.coreos.com/v1alpha1

FIELD:    repeatInterval <string>

DESCRIPTION:
     How long to wait before repeating the last notification. Must match the
     regular
     expression`^(([0-9]+)y)?(([0-9]+)w)?(([0-9]+)d)?(([0-9]+)h)?(([0-9]+)m)?(([0-9]+)s)?(([0-9]+)ms)?$`
     Example: "4h"



Version-Release number of selected component (if applicable):
tested with PR

How reproducible:
always

Steps to Reproduce:
1. see the description
2.
3.

Actual results:


Expected results:


Additional info: