Description of problem:
On atomic hosts, the oadm pathis /var/usrlocal/bin/oadm and /usr/local/bin/oadm.  But the path /usr/local/bin isn't in Environment PATH of root.  so we must use absolute path "/usr/local/bin/oadm" with root

On atomic, the oadm path is /var/usrlocal/bin/oadm or /usr/local/bin/oadm
On containerized Env on RHEL, the oadm path is  /usr/local/bin/oadm
On rpm Env on RHEL, the oadm path is  /usr/bin/oadm

Version-Release number of selected component (if applicable):
openshift/openshift-ansible: Pull Request 4492.


How reproducible:
always

Steps to Reproduce:
1. install OCP v3.5 on atomic. and use cloud-user to access instances.
   ansible_user=cloud-user 
   ansible_become=true
2. upgrade to v3.6
3. migrate etcd from v2 to v3
   anible-playbook openshift-ansible/playbooks/byo/openshift-etcd/migrate.yml

Actual results:
TASK [etcd_migrate : Enable etcd member] ***************************************
changed: [openshift-225.lab.eng.nay.redhat.com]

TASK [etcd_migrate : Re-introduce leases (as a replacement for key TTLs)] ******
failed: [openshift-225.lab.eng.nay.redhat.com] (item=/kubernetes.io/events) => {
    "cmd": "oadm migrate etcd-ttl --cert /etc/etcd/peer.crt --key /etc/etcd/peer.key --cacert /etc/etcd/ca.crt --etcd-address https://192.168.1.185:2379 --ttl-keys-prefix /kubernetes.io/events --lease-duration 1h", 
    "failed": true, 
    "item": "/kubernetes.io/events", 
    "rc": 2
}

MSG:

[Errno 2] No such file or directory

failed: [openshift-225.lab.eng.nay.redhat.com] (item=/kubernetes.io/masterleases) => {
    "cmd": "oadm migrate etcd-ttl --cert /etc/etcd/peer.crt --key /etc/etcd/peer.key --cacert /etc/etcd/ca.crt --etcd-address https://192.168.1.185:2379 --ttl-keys-prefix /kubernetes.io/masterleases --lease-duration 1h", 
    "failed": true, 
    "item": "/kubernetes.io/masterleases", 
    "rc": 2
}

MSG:

[Errno 2] No such file or directory

    to retry, use: --limit @/root/openshift-ansible/playbooks/byo/openshift-etcd/migrate.retry

PLAY RECAP *********************************************************************
localhost                  : ok=22   changed=0    unreachable=0    failed=0   
openshift-208.lab.eng.nay.redhat.com : ok=65   changed=1    unreachable=0    failed=0   
openshift-225.lab.eng.nay.redhat.com : ok=116  changed=9    unreachable=0    failed=1   

Expected results:


Additional info: