clean up foobazdmx role

make git repo url and version to check out a variable instead of a
hard-coded value the role, and update host_vars to match.

playbooks/roles/foobazdmx/tasks/main.yaml

@@ -24,9 +24,9 @@
     - name: Clone foobazdmx repository
       become: true
       ansible.builtin.git:
-        repo: https://ccchh-ansible:glpat-istRKj5ivdBs_u9Tsdbp@gitlab.hamburg.ccc.de/ccchh/foobazdmx.git
+        repo: "{{ foobazdmx_repo_url }}"
         dest: /opt/foobazdmx
-        version: main
+        version: "{{ foobazdmx_version }}"
     - name: Install python dependencies
       become: true
       become_user: foobazdmx