facts: use correct python interpreter

that task is delegated on the first mon so we should always use the
`discovered_interpreter_python` from that node.

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit 5adb735c78)

roles/ceph-facts/tasks/facts.yml

@@ -108,7 +108,7 @@
     - not rolling_update | bool
   block:
   - name: generate cluster fsid
-    command: "{{ discovered_interpreter_python }} -c 'import uuid; print(str(uuid.uuid4()))'"
+    command: "{{ hostvars[groups[mon_group_name][0]]['discovered_interpreter_python'] }} -c 'import uuid; print(str(uuid.uuid4()))'"
     register: cluster_uuid
     delegate_to: "{{ groups[mon_group_name][0] }}"
     run_once: true