Revert "remove max connection age"

This reverts commit b9b684194f.

weed/pb/grpc_client_server.go

@@ -48,6 +48,7 @@ func NewGrpcServer(opts ...grpc.ServerOption) *grpc.Server {
 		grpc.KeepaliveParams(keepalive.ServerParameters{
 			Time:             10 * time.Second, // wait time before ping if no activity
 			Timeout:          20 * time.Second, // ping timeout
+			MaxConnectionAge: 10 * time.Hour,
 		}),
 		grpc.KeepaliveEnforcementPolicy(keepalive.EnforcementPolicy{
 			MinTime:             60 * time.Second, // min time a client should wait before sending a ping