Temporarily disable V3 response diff logging (#1607)

This commit disables the logging of V3 response diffs by commenting out
the `log.Printf` statement in `internal/server/mirror.go`.

The corresponding test in `internal/server/mirror_test.go` has also been
updated to reflect this change. A `TODO` has been added to re-enable the
logging and the test once structured logging is in place.

Currently the diff takes up multiple log lines, and also it's not super
useful since Spanner Graph isn't being updated regularly. We'll get an
initial sample of diffs between today's release and the release that
contains this PR, and then we can re-enable when (a) we can use
structured logging for nicer diffs, and (b) Spanner Graph contents are
more up-to-date.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: hqpho

internal/server/mirror.go

@@ -124,7 +124,8 @@ func (s *Server) doMirror(
 	}
 
 	if diff := cmp.Diff(originalResp, v3Resp, protocmp.Transform()); diff != "" {
-		log.Printf("V3 mirrored call had a different response. V3 Method: %s, skipCache: %t, Diff: %s", rpcMethod, skipCache, diff)
+		// TODO(hqpho): Re-enable once structured logging is ready.
+		// log.Printf("V3 mirrored call had a different response. V3 Method: %s, skipCache: %t, Diff: %s", rpcMethod, skipCache, diff)
 		metrics.RecordV3Mismatch(ctx)
 	}
 }

internal/server/mirror_test.go

@@ -205,10 +205,12 @@ func TestMaybeMirrorV3_ResponseMismatch(t *testing.T) {
 	s.maybeMirrorV3(ctx, v2Req, v2Resp, 0, v3Call, &mirrorWg)
 	mirrorWg.Wait()
 
-	logOutput := buf.String()
-	if strings.Count(logOutput, "V3 mirrored call had a different response") != 2 {
-		t.Errorf("log output should contain 2 diff warnings, but got: %q", logOutput)
-	}
+	// logOutput := buf.String()
+	// TODO(hqpho): Re-enable this test once structured logging is ready and
+	// the V3 response diff logging is re-enabled.
+	// if strings.Count(logOutput, "V3 mirrored call had a different response") != 2 {
+	// 	t.Errorf("log output should contain 2 diff warnings, but got: %q", logOutput)
+	// }
 
 	var rm metricdata.ResourceMetrics
 	if err := reader.Collect(context.Background(), &rm); err != nil {