fix gofmt goimports go tool vet errors

clientconn.go

@@ -38,9 +38,9 @@ import (
 	"fmt"
 	"math"
 	"net"
+	"strings"
 	"sync"
 	"time"
-	"strings"
 
 	"golang.org/x/net/context"
 	"golang.org/x/net/trace"

test/end2end_test.go

@@ -1441,7 +1441,7 @@ func testServiceConfigMaxMsgSize(t *testing.T, e env) {
 		t.Fatalf("%v.FullDuplexCall(_) = _, %v, want <nil>", tc, err)
 	}
 	if err := stream.Send(sreq); err != nil {
-		t.Fatalf("%v.Send(%v) = %v, want <nil>", stream, err)
+		t.Fatalf("%v.Send(%v) = %v, want <nil>", stream, sreq, err)
 	}
 	sreq.Payload = extraLargePayload
 	if err := stream.Send(sreq); err == nil || grpc.Code(err) != codes.InvalidArgument {