### Multi destination replication

* Upgrade the default etcd server version to 3.1.12 to pick up critical etcd "mvcc "unsynced" watcher restore operation" fix. ([#60998](https://github.com/kubernetes/kubernetes/pull/60998), [@jpbetz](https://github.com/jpbetz))

proxy1     cluster1     STALE                          SYNCED       SYNCED                         NOT SENT     NOT SENT     istiod1     1.1
proxy2     cluster2     STALE                          SYNCED       STALE                          SYNCED       NOT SENT     istiod2     1.1
proxy3     cluster3     STALE (Never Acknowledged)     NOT SENT     STALE (Never Acknowledged)     SYNCED       NOT SENT     istiod3     1.1

NAME       CLUSTER      CDS       LDS        EDS       RDS        ECDS         ISTIOD      VERSION

NAME       CLUSTER      CDS       LDS        EDS       RDS        ECDS         ISTIOD      VERSION

NAME       CLUSTER      CDS       LDS        EDS        RDS          ECDS         ISTIOD      VERSION
proxy1     cluster1     STALE     SYNCED     SYNCED     NOT SENT     NOT SENT     istiod1     1.1

NAME       CLUSTER      CDS       LDS        EDS        RDS          ECDS         ISTIOD      VERSION
proxy1     cluster1     STALE     SYNCED     SYNCED     NOT SENT     NOT SENT     istiod1     1.20

A queue is used to give a few properties:
* Ability to serially process updates received from a variety of different sources. This avoids need for other synchronization mechanisms like mutexes.
* Correctness at startup; with the sequencing above, items are only processed once all informers are synced. This means queries will not return stale data at startup.

NAME       CLUSTER      CDS          LDS         EDS         RDS          ECDS         ISTIOD      VERSION
proxy1     cluster1     STALE        SYNCED      SYNCED      NOT SENT     SYNCED       istiod1     1.20
proxy2     cluster2     STALE        SYNCED      STALE       SYNCED       STALE        istiod2     1.19
proxy3     cluster3     NOT SENT     ERROR       STALE       NOT SENT     NOT SENT     istiod3     1.20

  protected Table<String, Integer, Character> create(@Nullable Object... data) {
    TestTable<String, Integer, Character> table = new TestTable<>();
    Table<String, Integer, Character> synced = Synchronized.table(table, table.mutex);
    populate(synced, data);
    return synced;
  }