This reverts commit bf144679.

Reason for revert: broke win bots http://o/410053

Original change's description:
> [win_tools] Use bundled Python CIPD packages.
> 
> Enable bundled Python CIPD packages in bleeding-edge mode. This
> replaces the ZIP unpacking approach used before, and introduces
> validation and management through the CIPD tool. The bleeding edge
> version will only install if a sentinel file is present in the
> "depot_tools" root; otherwise, default behavior will continue.
> 
> This method adds a upgrade and downgrade path to/from ZIP and
> CIPD installations. This is done by rewriting the "win_tools.bat"
> process:
> 
> 1) Ensure that a bootstrap Python is present.
> 2) Use it to run "win_tools.py", which has the functionality of
>     "git_bootstrap.py" plus Python installation.
> 3) Run "win_tools.py" with appropriate flags.
> 
> Some tricks were employed to handle cases where there is an
> already-running Python instance that uses the current Python
> installation and executable. This happens on bots because the
> system uses the same "depot_tools" checkout at multiple launch
> layers. To this end, we use the "python.bat" as the "current Python"
> authority and refrain from cleaning up old Python directories if their
> "python.exe" binaries are currently in use.
> 
> We change the Git bleeding edge file to share the same
> sentinel file as Python, ".bleeding_edge".
> 
> The new Python should have the same facilities as the original Python
> bundle.
> 
> BUG=chromium:740171
> TEST=local
> 
> Change-Id: I1b3b7d31d47d1a37a9dba9114d31681bec558736
> Reviewed-on: https://chromium-review.googlesource.com/563036
> Commit-Queue: Daniel Jacques <dnj@chromium.org>
> Reviewed-by: Robbie Iannucci <iannucci@chromium.org>

TBR=iannucci@chromium.org,dnj@chromium.org

Change-Id: I84574a01bbad6596912e4aaa34f019d24720b638
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:740171
Reviewed-on: https://chromium-review.googlesource.com/567009Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>