Actually don't embed prepare.yml

It can be customised if needed, otherwise not used.

molecule_hetznercloud/playbooks/prepare.yml

@@ -1,9 +0,0 @@
----
-- name: Prepare
-  hosts: all
-  gather_facts: false
-  tasks:
-    - name: Install python for Ansible
-      raw: test -e /usr/bin/python || (apt -y update && apt install -y python-minimal python-zipstream)
-      become: true
-      changed_when: false