Fixes 6621 etcd backup directory is consuming much rootfs disk space (#6836)

* added an ansible var to manage retention of etcd backups

* refactord ls/grep into find in etcd backup removal command

roles/etcd/handlers/backup.yml

@@ -8,6 +8,7 @@
     - Stat etcd v2 data directory
     - Backup etcd v2 data
     - Backup etcd v3 data
+    - Remove old etcd backups
   when: etcd_cluster_is_healthy.rc == 0
 
 - name: Refresh Time Fact
@@ -57,3 +58,9 @@
   register: etcd_backup_v3_command
   until: etcd_backup_v3_command.rc == 0
   delay: "{{ retry_stagger | random + 3 }}"
+
+- name: Remove old etcd backups
+  shell:
+    chdir: "{{ etcd_backup_prefix }}"
+    cmd: "find . -name 'etcd-*' | head -n -{{ etcd_backup_retention_count }} | xargs rm -rf"
+  when: etcd_backup_retention_count >= 0