This reverts commit 028367fe.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> depot_tools: Use vpython to execute fetch.
> 
> Bug: 1002153
> Change-Id: I11286bebc23bedada239d6ddb8ebb86207a41485
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1815707
> Reviewed-by: Anthony Polito <apolito@google.com>
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
> Auto-Submit: Edward Lesmes <ehmaldonado@chromium.org>

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

Change-Id: I0924e77a3862b8a75195db7fe719286e1cb3ac7e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1002153
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1824217Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>