postfix: Remove empty files

roles/postfix/files/access_client

roles/postfix/files/access_helo

roles/postfix/files/access_recipient

roles/postfix/files/access_sender

roles/postfix/files/access_sender-post-filter

roles/postfix/files/body_checks

roles/postfix/files/header_checks

roles/postfix/files/relocated

roles/postfix/handlers/main.yml

roles/postfix/tasks/main.yml

roles/postfix/templates/main.cf.j2

roles/postfix/templates/users.pcre.j2