[fuchsia] Switch http_service_tests to use a real clock.

* The http_service_tests suite was incorrectly switched to use
  IO_MOCK_TIME rather than IO. A change in Fuchsia netstack uncovered
  the issue.
* Improve log output when the test expectations are incorrect by
  displaying the network error.
* Lower MultipleRequests to handle 10 concurrent requests, down from
  100, to prevent TimeOut issues.

Change-Id: I71a801eb72290e5048087b2ee8b442e3418f5b13
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1696171
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676678}
1 file changed