Description of problem:
OCP 4.4 on OSP16 fails with error:

INFO Cluster operator monitoring Progressing is True with RollOutInProgress: Rolling out the s
tack.                                                                                         
ERROR Cluster operator monitoring Degraded is True with UpdatingAlertmanagerFailed: Failed to 
rollout the stack. Error: running task Updating Alertmanager failed: waiting for Alertmanager
Route to become ready failed: waiting for RouteReady of alertmanager-main: no status available
 for alertmanager-main                                                                        
FATAL failed to initialize the cluster: Working towards 4.4.0-0.nightly-2020-03-01-212047: 99%
 complete 

$ oc logs -n openshift-machine-api machine-api-controllers-8d874cb86-z8xp6 -c machine-controller

E0303 11:41:28.528641       1 controller.go:279] Failed to check if machine "ocpra-vbmm9-worker-2lbhd" exists: Error checking if instance exists (machine/actuator.go 346):                 
Error getting a new instance service from the machine (machine/actuator.go 467): Failed to authenticate provider client: Get https://openstack.home.lab:13000/: dial tcp: lookup openstack.home.lab on 172.30.0.10:53: no such host 

Config file DNS section:

platform:
  openstack:                                                                                 
    cloud: openstack                                                                         
    computeFlavor: m1.large                                                                  
    externalDNS: ['172.31.8.1','8.8.8.8']



Version-Release number of the following components:
OCP 4.4.0-0.nightly-2020-03-01-212047

Based on this doc -> https://coredns.io/plugins/forward/
The default policy is random, meaning that if it picks 8.8.8.8
resolver that won't be able to resolve your cluster hostname

We should change it to default to first parameter and only use the second one if the first one fails

How reproducible:
Everytime

Steps to Reproduce:
1. Deploy OCP 4.4 with 2 dns entries where only one of the dns resolved overcloud domain name


Actual results:
failed

Expected results:
only use first dns unless first dns is not accessible 

Additional info: