CHANGELOG: Add v3.4.3
CHANGELOG: Add v3.4.3

Add v3.4.3 and fix v3.4.2 release date.

Fixes # 11353

mkumatag/etcd,coreos/etcd,coreos/etcd,etcd-io/etcd,gyuho/etcd,li-ang/etcd,mqliang/etcd,li-ang/etcd,mkumatag/etcd,rnaveiras/etcd,mqliang/etcd,dannysauer/etcd,cockroachdb/etcd,dannysauer/etcd,mqliang/etcd,mkumatag/etcd,ajityagaty/etcd,ajityagaty/etcd,ajityagaty/etcd,rnaveiras/etcd,cockroachdb/etcd,gyuho/etcd,etcd-io/etcd,etcd-io/etcd,rnaveiras/etcd