Turn on a WPR flag to stablize captured sites tests.

In
https://chromium.googlesource.com/catapult/+/734e7ea0cbf9e0965596350ea51e5b4c8fc623f0,
I introduced a change to Web page Replay Go (WPR Go) to prefer previously
unmatched responses. This change fixed a number of issues with capturing
checkout workflows on captured sites. The change hides the fix behind a
feature flag for compatibility reasons.

This change enables the fix by turning on the feature flag in Captured
Sites tests.

Bug: 850756
Change-Id: I0331b3b5cfe8b0ddde84211bd0b320ef65faa8fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574358
Auto-Submit: Yiming Zhou <uwyiming@google.com>
Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Commit-Queue: Fabio Tirelo <ftirelo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652291}

chrome/browser/autofill/captured_sites_test_utils.cc

@@ -338,6 +338,7 @@ 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");
   args.push_back(base::StringPrintf(
       "--inject_scripts=%s,%s",
       FilePathToUTF8(src_dir.AppendASCII("third_party")