Enforces locale overrides on all playbooks

Porting the locale override logic by @rmol to the usual medley of
SecureDrop prod playbooks. Correspondingly updates the config tests to
reuse the "all prod playbooks" lookup logic, so we're sure to retain
coverage into the future.

(cherry picked from commit c71bf16)

install_files/ansible-base/securedrop-backup.yml

@@ -3,6 +3,8 @@
   hosts: securedrop_application_server
   max_fail_percentage: 0
   any_errors_fatal: yes
+  environment:
+    LC_ALL: C
   roles:
     - role: backup
       tags: backup

install_files/ansible-base/securedrop-logs.yml

@@ -4,6 +4,8 @@
   become: yes
   max_fail_percentage: 0
   any_errors_fatal: yes
+  environment:
+    LC_ALL: C
   vars:
     log_paths_reference:
       app:

install_files/ansible-base/securedrop-restore.yml

@@ -3,6 +3,8 @@
   hosts: securedrop_application_server
   max_fail_percentage: 0
   any_errors_fatal: yes
+  environment:
+    LC_ALL: C
   roles:
     - role: restore
       tags: restore

install_files/ansible-base/securedrop-tails.yml

@@ -8,6 +8,8 @@
   any_errors_fatal: yes
   connection: local
   gather_facts: yes
+  environment:
+    LC_ALL: C
   roles:
     - role: tails-config
       tags: tails-config

molecule/ansible-config/tests/test_play_configuration.py

@@ -80,14 +80,11 @@ def test_any_errors_fatal(host, playbook):
             assert play['any_errors_fatal']
 
 
-@pytest.mark.parametrize('playbook', ['securedrop-prod.yml', 'securedrop-staging.yml'])
+@pytest.mark.parametrize('playbook', find_ansible_playbooks())
 def test_locale(host, playbook):
     """
     The securedrop-prod and securedrop-staging playbooks should
     control the locale in the host environment by setting LC_ALL=C.
-
-    TODO: evaluate whether to do the same for the rest of the
-    playbooks.
     """
     with io.open(os.path.join(ANSIBLE_BASE, playbook), 'r') as f:
         playbook_yaml = yaml.safe_load(f)