Remove orphaned http/OWNERS

Upstream dir went away in https://github.com/w3c/web-platform-tests/pull/10870.

No-Try: true
Change-Id: I5e37b453e96feaa4c491283e331ea36c00bba922
Reviewed-on: https://chromium-review.googlesource.com/1068677Reviewed-by: Yoav Weiss <yoav@yoav.ws>
Commit-Queue: Philip Jägenstedt <foolip@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561026}

third_party/WebKit/LayoutTests/external/wpt/http/OWNERS

-# TEAM: loading-dev@chromium.org
-# COMPONENT: Blink>Loader