Remove ceph-pg from openstack tripleo validator run groups

By design this validation will never suceed when run by openstack
tripleo validator run and thus it should be removed from the groups
that would cause it to be run this way.

Change-Id: I4ad2c6efe18a2cc63c6fa5189d420d7a2be1f753
Closes-Bug: #1900713

.ansible-lint

@@ -1,5 +1,6 @@
 exclude_paths:
     - releasenotes/
+    - playbooks/ceph-pg.yaml
 parseable: true
 quiet: false
 rulesdir:
@@ -22,4 +23,4 @@ skip_list:
     - '702'
     # meta/main.yml default values should be changed
     - '703'
-verbosity: 1
+verbosity: 1

playbooks/ceph-pg.yaml

@@ -14,9 +14,7 @@
         of OSD. Without this check a deployer may have to wait until after Ceph
         is running but before the pools are created to realize the deployment
         will fail.
-      groups:
-        - pre-deployment
-        - post-ceph
+      groups: []
   tasks:
     - include_role:
         name: ceph