ara_api role: provide sensible PATH defaults without venv

When deploying without a virtualenv, we need to supply a PATH where the
python and ara-manage binaries are likely to be found.

Change-Id: Ie9b498f988a026a2568cc445ef444fe2f90c837b

roles/ara_api/tasks/config.yaml

@@ -49,7 +49,7 @@
   block:
     - name: Generate a random secret key
       environment:
-        PATH: "{{ path_with_virtualenv | default(omit) }}"
+        PATH: "{{ path_with_virtualenv | default('/usr/bin:/usr/local/bin') }}"
       command: python3 -c "from django.utils.crypto import get_random_string; print(get_random_string(length=50))"
       no_log: yes
       register: generated_key

roles/ara_api/tasks/database_engine/django.db.backends.mysql.yaml

@@ -45,5 +45,5 @@
 - name: Run SQL migrations
   environment:
     ARA_SETTINGS: "{{ ara_api_settings }}"
-    PATH: "{{ path_with_virtualenv | default(omit) }}"
+    PATH: "{{ path_with_virtualenv | default('/usr/bin:/usr/local/bin') }}"
   command: ara-manage migrate

roles/ara_api/tasks/database_engine/django.db.backends.postgresql.yaml

@@ -45,5 +45,5 @@
 - name: Run SQL migrations
   environment:
     ARA_SETTINGS: "{{ ara_api_settings }}"
-    PATH: "{{ path_with_virtualenv | default(omit) }}"
+    PATH: "{{ path_with_virtualenv | default('/usr/bin:/usr/local/bin') }}"
   command: ara-manage migrate

roles/ara_api/tasks/database_engine/django.db.backends.sqlite3.yaml

@@ -26,5 +26,5 @@
   become: "{{ (ansible_user_dir in ara_api_database_name) | ternary(false, true) }}"
   environment:
     ARA_SETTINGS: "{{ ara_api_settings }}"
-    PATH: "{{ path_with_virtualenv | default(omit) }}"
+    PATH: "{{ path_with_virtualenv | default('/usr/bin:/usr/local/bin') }}"
   command: ara-manage migrate

tests/test_tasks.yaml

@@ -49,8 +49,8 @@
 
 - name: Get ARA plugins directory
   environment:
-    PATH: "{{ path_with_virtualenv | default(omit) }}"
-  command: python -m ara.setup.plugins
+    PATH: "{{ path_with_virtualenv | default('/usr/bin:/usr/local/bin') }}"
+  command: python3 -m ara.setup.plugins
   changed_when: false
   register: ara_setup_plugins