Fix cassandra_mapping.yaml reference for cutoutcass nodes

[genghisken]

The cutoutcass nodes are missing the reference to the cassandra_mapping.yaml file in deploy.yaml. (The file ensures that cassandra nodes are mapped to the correct hypervisor.) Just needs one file reference added under vars_files as below.

- hosts: cutoutcass
  gather_facts: false
  vars_files:
    - settings.yaml
    - cassandra_mapping.yaml
  vars:
    cassandra_cluster_name: "{{ group_names[0] }}"
    cassandra_commitlog_dir: /var/lib/cassandra-commitlog
  roles:
    - gkansible.gkservercollection.cassandra4
  tags: cutoutcass