Revert "Implement notifies for transfer plugin (#3972)" (#3995)

This reverts commit 68f1dd5ddf.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

plugin/kubernetes/kubernetes.go

@@ -46,6 +46,7 @@ type Kubernetes struct {
 	primaryZoneIndex int
 	localIPs         []net.IP
 	autoPathSearch   []string // Local search path from /etc/resolv.conf. Needed for autopath.
+	TransferTo       []string
 }
 
 // New returns a initialized Kubernetes. It default interfaceAddrFunc to return 127.0.0.1. All other
@@ -494,12 +495,6 @@ func (k *Kubernetes) findServices(r recordRequest, zone string) (services []msg.
 	return services, err
 }
 
-// Serial return the SOA serial.
-func (k *Kubernetes) Serial(state request.Request) uint32 { return uint32(k.APIConn.Modified()) }
-
-// MinTTL returns the minimal TTL.
-func (k *Kubernetes) MinTTL(state request.Request) uint32 { return k.ttl }
-
 // match checks if a and b are equal taking wildcards into account.
 func match(a, b string) bool {
 	if wildcard(a) {