all: remove redundant string conversions when formatting []byte with %s

Change-Id: I1285ee047fd465f48028186ae04d4de60cc9969e
Reviewed-on: https://go-review.googlesource.com/c/go/+/569715
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: shuang cui <imcusg@gmail.com>
Reviewed-by: Damien Neil <dneil@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/covdata/tool_test.go

@@ -294,7 +294,7 @@ func runToolOp(t *testing.T, s state, op string, args []string) []string {
 	cmd := testenv.Command(t, s.tool, args...)
 	b, err := cmd.CombinedOutput()
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "## %s output: %s\n", op, string(b))
+		fmt.Fprintf(os.Stderr, "## %s output: %s\n", op, b)
 		t.Fatalf("%q run error: %v", op, err)
 	}
 	output := strings.TrimSpace(string(b))

src/cmd/dist/testjson.go

@@ -99,7 +99,7 @@ func (f *testJSONFilter) process(line []byte) {
 				data, err := json.Marshal(val)
 				if err != nil {
 					// Should never happen.
-					panic(fmt.Sprintf("failed to round-trip JSON %q: %s", string(line), err))
+					panic(fmt.Sprintf("failed to round-trip JSON %q: %s", line, err))
 				}
 				f.w.Write(data)
 				// Copy any trailing text. We expect at most a "\n" here, but

src/net/http/cgi/host.go

@@ -277,7 +277,7 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		headerLines++
 		header, val, ok := strings.Cut(string(line), ":")
 		if !ok {
-			h.printf("cgi: bogus header line: %s", string(line))
+			h.printf("cgi: bogus header line: %s", line)
 			continue
 		}
 		if !httpguts.ValidHeaderFieldName(header) {