Use inventory_hostname for Ceph bootstrap

The inventory_hostname is more reliable than ansible_hostname for the
way we use it here. If the deploy node cannot resolve the hostname of a
target node (the operator is using IP addresses in their inventory), the
bootstrap will fail with:

"Host: x.x.x.x, Task: ceph : Fetching Ceph keyrings, Status:
unreachable, Message: SSH Error: data could not be sent to the remote
host.  Make sure this host can be reached over ssh"

Closes-Bug: 1599138
Change-Id: Ic76e4baf8c642c59bbe81e6671ac97bcbb57d470

ansible/roles/ceph/tasks/bootstrap_mons.yml

@@ -19,7 +19,7 @@
   register: ceph_mon_config_volume
 
 - name: Writing hostname of host with existing cluster files to temp file
-  local_action: copy content={{ ansible_hostname }} dest=/tmp/kolla_ceph_cluster mode=0600
+  local_action: copy content="{{ inventory_hostname }}" dest=/tmp/kolla_ceph_cluster mode=0600
   changed_when: False
   always_run: True
   when: not ceph_mon_config_volume.changed

ansible/roles/ceph/tasks/generate_cluster.yml

@@ -25,4 +25,4 @@
 
 - name: Setting host for cluster files
   set_fact:
-    delegate_host: "{{ ansible_hostname }}"
+    delegate_host: "{{ inventory_hostname }}"