Add auto_compaction for maintenance etcd (#562)

Automate the maintenance of etcd cluster. Namely, the addition of automatic compression of the etcd database.

> Since etcd keeps an exact history of its keyspace, this history should be periodically compacted to avoid performance degradation and eventual storage space exhaustion.

More detail here: https://etcd.io/docs/v3.5/op-guide/maintenance/

roles/etcd/templates/etcd.conf.j2

@@ -10,3 +10,4 @@ ETCD_DATA_DIR="{{ etcd_data_dir }}"
 ETCD_ELECTION_TIMEOUT="5000"
 ETCD_HEARTBEAT_INTERVAL="1000"
 ETCD_INITIAL_ELECTION_TICK_ADVANCE="false"
+ETCD_AUTO_COMPACTION_RETENTION="1"