Description of problem:
Install OCP 4.6.0-0.nightly-2020-09-15-045818 and scaleup rhel worker with rhel7.7 template on vsphere, new worker's CSR could not be approved.

We detected that nameserver in /etc/resolv.conf is empty after rebooting worker node per below task, so there are many errors of failing pull image in /var/log/message.

TASK [openshift_node : Reboot the host and wait for it to come back] ***********
Tuesday 15 September 2020  21:50:18 +0800 (0:00:01.730)       0:28:33.451 ***** 
changed: [136.144.52.245] => {"changed": true, "elapsed": 37, "rebooted": true}

TASK [openshift_node : Approve node CSRs] **************************************
Tuesday 15 September 2020  21:50:58 +0800 (0:00:40.651)       0:29:14.102 ***** 
fatal: [136.144.52.245]: FAILED! => {"changed": false, "client_approve_results": ["Attempt: 1, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", "Attempt: 2, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", "Attempt: 3, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", "Attempt: 4, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", "Attempt: 5, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", "Attempt: 6, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", "Attempt: 7, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", "Attempt: 8, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", "Attempt: 9, Node jima091501-x7q9g-rhel-0 not present or CSR not yet available", ...}

# cat /etc/resolv.conf
# Generated by NetworkManager

RHEL worker uses dhcp, network information comes from dhcp server, and /etc/resolv.conf is updated by NetworkManager.
We found that NetworkManager config file 30-resolv-prepender has been updated per PR: https://github.com/openshift/machine-config-operator/commit/03c880054238fa41ef07396fdce9f03134c9f98d

I tried to remove new lines introduced above PR, and restart node, /etc/resolv.conf becomen normal and get correct nameserver. 

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


How reproducible:
Always

Steps to Reproduce:
1. Install OCP 4.6.0-0.nightly-2020-09-15-045818
2. Scaleup rhel worker with RHEL7.7 template.
3.

Actual results:
Could not approve worker node's CSR

Expected results:
worker node is joined successfully

Additional info: