Description of problem:

metrics-server was uninstalled to update its certificates (secret/metrics-server-certs), but "metrics-server-certs" is remained due to a incorrect label.

* The uninstall task is selecting the targets with "--selector=metrics-server-infra".

// "roles/metrics_server/tasks/uninstall_metrics_server.yaml"
~~~
- name: remove metrics-server components
  command: >
    {{ openshift_client_binary }} -n {{ openshift_metrics_server_project }} --config={{ mktemp.stdout }}/admin.kubeconfig
    delete --ignore-not-found --selector=metrics-server-infra
    all,sa,secrets,rolebindings,clusterrolebindings,clusterrole,apiservice,deployment
  register: delete_metrics_server
  changed_when: delete_metrics_server.stdout != 'No resources found'

~~~

BUT the "metrics-server-certs" labeled as "metrics-infra", not "metrics-server-infra".

// roles/metrics_server/templates/serving-certs-secret.j2
~~~
apiVersion: v1
kind: Secret
metadata:
  name: metrics-server-certs
  labels:
    metrics-infra: metrics-server
data:
  tls.crt: {{ cert }}
  tls.key: {{ key }}
  ca.crt: {{ ca }}

~~~

Version-Release number of the following components:
rpm -q openshift-ansible

openshift-ansible-3.11.135-1.git.0.b7ad55a.el7

rpm -q ansible

ansible-2.6.19-1.el7ae.noarch

ansible --version

ansible 2.6.19
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 2.7.5 (default, May 31 2018, 09:41:32) [GCC 4.8.5 20150623 (Red Hat 4.8.5-28)]


How reproducible:

You can always reproduce to run the playbooks as follows.

1> uninstall metrics-server

# ansible-playbook -i <inventory file path> playbooks/metrics-server/config.yml -e openshift_metrics_server_install=false

2> You can see the secret to remain after uninstall.
# oc get secret metrics-server-certs -n openshift-metrics-server
NAME                   TYPE      DATA      AGE
metrics-server-certs   Opaque    3         26d

Steps to Reproduce:
1.
2.
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Actual results:

After uninstall metrics-server, only "metrics-server-certs" is remaining.

Expected results:

All metrics-server components are removed including "metrics-server-certs" secret after uninstall metrics-server.

Additional info: