[FEATURE] Add scenario to backup VM Cluster from ansible

[denisgolius]

It wold be great to have the same functionality to run backups in VM Cluster as it works for VM Single node, see -

ansible-playbooks/roles/single/tasks/configure.yml

Lines 74 to 82 in dad26c7

	- name: Configure cron
	cron:
	name: "backup victoriametrics data"
	user: root
	state: present
	hour: "{{ victoriametrics_backup_cron_hour }}"
	job: "{{ _victoria_backup_proxy | default(omit) }} /usr/local/bin/vmbackup-prod -snapshot.createURL=http://localhost:8428/snapshot/create {% if victoriametrics_backup_custom_s3_endpoint != '' %} -customS3Endpoint {{ victoriametrics_backup_custom_s3_endpoint }} {% endif %} -storageDataPath {{ victoriametrics_data_dir }} -dst {{ victoriametrics_backup_destination }}/$(date +\\%Y-\\%m-\\%d)"
	when: victoriametrics_backup_enabled | bool