OpenShift Metrics install fails when variable openshift_hosted_metrics_public_url set

Issue

When the deprecated variable openshift_hosted_metrics_public_url is set in the inventory file metrics install fails with:

TASK [openshift_metrics : Applying /tmp/openshift-metrics-ansible-Rh594H/templates/hawkular-metrics-route.yaml] *********************************************************
fatal: [njrarltapp0017d.linux.us.ams1907.com]: FAILED! => {"changed": false, "cmd": ["oc", "--config=/tmp/openshift-metrics-ansible-Rh594H/admin.kubeconfig", "apply", "-f", "/tmp/openshift-metrics-ansible-Rh594H/templates/hawkular-metrics-route.yaml", "-n", "openshift-metrics"], "delta": "0:00:00.314354", "end": "2018-08-03 11:20:45.485442", "failed": true, "failed_when_result": true, "msg": "non-zero return code", "rc": 1, "start": "2018-08-03 11:20:45.171088", "stderr": "The Route \"hawkular-metrics\" is invalid: spec.host: Invalid value: \"https://hawkular-metrics-njrar-02.paas-stress.ams1907.com/hawkular/metrics\": host must conform to DNS 952 subdomain conventions", "stderr_lines": ["The Route \"hawkular-metrics\" is invalid: spec.host: Invalid value: \"https://hawkular-metrics-njrar-02.paas-stress.ams1907.com/hawkular/metrics\": host must conform to DNS 952 subdomain conventions"], "stdout": "", "stdout_lines": []}
        to retry, use: --limit @/root/openshift-cluster-39-stress/config.retry

This issue is described by Bugzilla 1581766.