[Services] AJAX/fetch request timing in HUD doesn't match client

[philliphoff]

The timing data reported for AJAX and fetch requests do not match that shown in the client, either as web requests of the originating request or requests themselves.

Notice the AJAX request with timing 1604ms:

This AJAX request shows up as a web service call in the originating request with duration 729.83ms:

This AJAX request itself shows up with a duration of 704.87ms:

Image from #157:

[philliphoff]

This is a dupe of #157.