fix(bigtable): fix #4338 by removing obsolete with block (#4353)

bigtable/bigtable.go

@@ -79,9 +79,7 @@ func NewClientWithConfig(ctx context.Context, project, instance string, config C
 		option.WithGRPCConnectionPool(4),
 		// Set the max size to correspond to server-side limits.
 		option.WithGRPCDialOption(grpc.WithDefaultCallOptions(grpc.MaxCallSendMsgSize(1<<28), grpc.MaxCallRecvMsgSize(1<<28))),
-		// TODO(grpc/grpc-go#1388) using connection pool without WithBlock
-		// can cause RPCs to fail randomly. We can delete this after the issue is fixed.
-		option.WithGRPCDialOption(grpc.WithBlock()))
+	)
 	// Attempts direct access to spanner service over gRPC to improve throughput,
 	// whether the attempt is allowed is totally controlled by service owner.
 	o = append(o, internaloption.EnableDirectPath(true))