Description of problem:
openshift-logging/config.yml ignores variable openshift_logging_es_pvc_storage_class_name since openshift-ansible version 3.11.123-1.


Version-Release number of selected component (if applicable):
openshift-ansible version 3.11.123-1+ (3.11.129-1, 3.11.135-1)

How reproducible:
100%

Steps to Reproduce:
1. Use any of the playbook versions listed above.
2. Create a non-default storage class, i.e., "glusterfs-test"
3. Set your inventory file to use this SC, i.e.:

~~~
openshift_logging_install_logging=true
openshift_logging_kibana_nodeselector={"node-role.kubernetes.io/infra": "true"}
openshift_logging_curator_nodeselector={"node-role.kubernetes.io/infra": "true"}
openshift_logging_es_nodeselector={"node-role.kubernetes.io/infra": "true"}
openshift_logging_curator_default_days=30
openshift_logging_es_cluster_size=3
openshift_logging_es_memory_limit=2G
openshift_logging_elasticsearch_cpu_limit=1000m
openshift_logging_es_pvc_dynamic=true
openshift_logging_es_pvc_storage_class_name=glusterfs-test
openshift_logging_es_pvc_size=1Gi
openshift_logging_es_allow_external=true
~~~

4. Execute the config.yml playbook. 

Actual results:
PVs are created using the default storage class, instead of the one set in openshift_logging_es_pvc_storage_class_name

Expected results:

PVs should be using glusterfs-test SC instead of the default one. 

Additional info:

You can confirm this by downgrading openshift-ansible package to 3.11.104-1:
 
- Uninstall the current deployment (removing the PVs)
- Downgrade openshift-ansible package: 
$ sudo yum remove openshift-ansible -y 
$ sudo yum install openshift-ansible-3.11.104-1.git.0.379a011.el7 -y 
- Re-try the deployment, PVs will be created with the correct SC.