Revert of bot_update/gclient: kill git fetch after timeout regardless of output. (patchset #2 id:20001 of https://codereview.chromium.org/2293013002/ )

Reason for revert:
didn't work.

Original issue's description:
> bot_update/gclient: kill git fetch after timeout regardless of output.
>
> Also spits out whatever output was produced by git fetch for debugging.
>
> BUG=635641
> R=machenbach@chromium.org,hinoka@chromium.org
>
> Committed: https://chromium.googlesource.com/chromium/tools/depot_tools/+/db8b839320168ab4f5156399ecb275478c0aa2cd

TBR=hinoka@chromium.org,machenbach@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=635641

Review-Url: https://codereview.chromium.org/2410053002