distro/tests: fix file permissions set by ansible

Ansible switched default file perm to 600 from more permissive 666. Add file mode explicitly to avoid issues.

@jruzicka Please try to trigger the right pipeline to verify these changes fix all issues and all distro tests now pass.

Also, the ansible role to configure repository is copied in Knot DNS, so I have to fix issue like this in multiple places (knot-dns!1167 (merged)). It'd be nice if some future solution wouldn't require that.

merged

mentioned in commit e5ee06c2