This reverts commit 7fd6347b.

Reason for revert: This broke Flutter CI - we're not using vpython everywhere yet

Original change's description:
> depot_tools: Remove third_party/httplib2.
> 
> depot_tools' scripts have been using vpython httplib2 for a while.
> 
> Change-Id: I9403d92332c74de0ed69d6f59f60c81772d0577a
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1978983
> Reviewed-by: Anthony Polito <apolito@google.com>
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

TBR=ehmaldonado@chromium.org,apolito@google.com

Change-Id: Ie53a8d07ccfba5a7cc5bcb431d4f7b897f66788a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1989012Reviewed-by: Dan Field <dnfield@google.com>
Commit-Queue: Dan Field <dnfield@google.com>