ci: Set LANG environment variable

Hopefully this will fix this warning from Ansible:

> [WARNING]: An error occurred while calling
> ansible.utils.display.initialize_locale (unsupported locale setting).
> This may result in incorrectly calculated text widths that can cause
> Display to print incorrect line lengths

vars/applyConfigPolicy.groovy

@@ -15,6 +15,9 @@ def call(rw_limit, stages) {
                     image: 'git.pyrocufflink.net/containerimages/ansible',
                     command: 'sleep',
                     args: 'infinity',
+                    envVars: [
+                        envVar(key: 'LANG', value: 'C.UTF-8'),
+                    ],
                 )
             ]) {
                 node(POD_LABEL) {