Define install_method default when hosts resolution depend on it

In some playbooks we try to fetch openstack_service_setup_host based on
install_method variable. However, if variable is not defined,
and it is not by default, playbooks will run against localhost,
which will result in failure.

Closes-Bug: #2031647
Change-Id: I247ce2a808076ff55347db54327a1e4913ea3006

playbooks/ceph-rgw-keystone-setup.yml

@@ -17,7 +17,7 @@
   hosts: "{{ openstack_service_setup_host | default('localhost') }}"
   user: root
   vars_files:
-    - "defaults/{{ install_method }}_install.yml"
+    - "defaults/{{ install_method | default('source') }}_install.yml"
   vars:
     ansible_python_interpreter: >-
       {{ openstack_service_setup_host_python_interpreter |

playbooks/healthcheck-infrastructure.yml

@@ -102,7 +102,7 @@
   hosts: "{{ openstack_service_setup_host | default('localhost') }}"
   gather_facts: no
   vars_files:
-    - "defaults/{{ install_method }}_install.yml"
+    - "defaults/{{ install_method | default('source') }}_install.yml"
   vars:
     ansible_python_interpreter: "{{ openstack_service_setup_host_python_interpreter | default(ansible_facts['python']['executable']) }}"
   tasks:

playbooks/os-keystone-install.yml

@@ -23,7 +23,7 @@
   hosts: "{{ openstack_service_setup_host | default('localhost') }}"
   gather_facts: "{{ osa_gather_facts | default(True) }}"
   vars_files:
-    - "defaults/{{ install_method }}_install.yml"
+    - "defaults/{{ install_method | default('source') }}_install.yml"
   become: yes
   tags:
     - openrc