prevent unsupported locale setting error in GHA

related to https://github.com/ansible/ansible/pull/78175

the way the GHA runner is built, Python runs with a mixed locale between the FS bits and the default encoding, which can cause unpredictable issues

adding env var `LC_ALL: "C.UTF-8"` prevent flakiness due to locale issue

Signed-off-by: Hao Liu <haoli@redhat.com>

.github/workflows/e2e_test.yml

@@ -1,5 +1,8 @@
 ---
 name: E2E Tests
+env:
+  LC_ALL: "C.UTF-8" # prevent ERROR: Ansible could not initialize the preferred locale: unsupported locale setting
+
 on:
   pull_request_target:
     types: [labeled]