Do not use ‘yes/no’ for boolean values (#11472)

Consistent boolean values in ansible playbooks

roles/etcd/tasks/install_docker.yml

@@ -29,7 +29,7 @@
     dest: "{{ bin_dir }}/etcd"
     owner: 'root'
     mode: "0750"
-    backup: yes
+    backup: true
   when: etcd_cluster_setup
 
 - name: Install etcd-events launch script
@@ -38,5 +38,5 @@
     dest: "{{ bin_dir }}/etcd-events"
     owner: 'root'
     mode: "0750"
-    backup: yes
+    backup: true
   when: etcd_events_cluster_setup