set the quiet_mode flag for wpr during captured sites replay

This flag will spin up WPR in quiet mode, so that the log doesn't
balloon with basic stdout call and response information

This helps the readability and usefulness of the logs for diagnosing issues

Bug: 988509
Change-Id: Ibc195ed4bb135ecdb07e78d0bae7e5701e240917
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1747863
Commit-Queue: Ian Struiksma <ianstruiksma@google.com>
Auto-Submit: Ian Struiksma <ianstruiksma@google.com>
Reviewed-by: Maxim Kolosovskiy <kolos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686489}

chrome/browser/autofill/captured_sites_test_utils.cc

@@ -449,6 +449,10 @@ bool TestRecipeReplayer::StartWebPageReplayServer(
   args.push_back(base::StringPrintf("--http_port=%d", kHostHttpPort));
   args.push_back(base::StringPrintf("--https_port=%d", kHostHttpsPort));
   args.push_back("--serve_response_in_chronological_sequence");
+  // Start WPR in quiet mode, removing the extra verbose ServeHTTP interactions
+  // that are for the the overwhelming majority unhelpful, but for extra
+  // debugging of a test case, this might make sense to comment out.
+  args.push_back("--quiet_mode");
   args.push_back(base::StringPrintf(
       "--inject_scripts=%s,%s",
       FilePathToUTF8(src_dir.AppendASCII("third_party")