Give PV & PVC empty storage class to avoid being assigned default gp2

roles/openshift_provisioners/templates/pv.j2

@@ -30,3 +30,4 @@ spec:
     name: {{claim_name}}
     namespace: {{openshift_provisioners_project}}
 {% endif %}
+  storageClassName: ""

roles/openshift_provisioners/templates/pvc.j2

@@ -23,4 +23,5 @@ spec:
   resources:
     requests:
       storage: {{size}}
+  storageClassName: ""