Read "$_POST" before hooking the profiler, and remove "aphront.default-application-configuration-class"

Summary:
Ref T4369. Ref T12297. Ref T13242. Ref PHI1010. I want to take a quick look at transaction.search and see if there's anything quick and obvious we can do to improve performance.

On secure, the __profile__ flag does not survive POST like it's supposed to: when you profile a page and then submit a form on the page, the result is supposed to be profiled. The intent is to make it easier to profile Conduit calls.

I believe this is because we're hooking the profiler, then rebuilding POST data a little later -- so $_POST['__profile__'] isn't set yet when the profiler checks.

Move the POST rebuild a little earlier to fix this.

Also, remove the very ancient "aphront.default-application-configuration-class". I believe this was only used by Facebook to do CIDR checks against corpnet or something like that. It is poorly named and long-obsolete now, and AphrontSite does everything we might reasonably have wanted it to do.

Test Plan: Poked around locally without any issues. Will check if this fixes the issue on secure.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13242, T12297, T4369

Differential Revision: https://secure.phabricator.com/D20046