This reverts commit b2bfd55f.

Reason for revert: not responsible for crbug.com/1025659

Original change's description:
> Revert "depot_tools: Ensure Python is bootstrapped before reading python3_bin_reldir.txt"
> 
> This reverts commit bf26b167.
> 
> Reason for revert: spec revert for https://bugs.chromium.org/p/chromium/issues/detail?id=1025659
> 
> Original change's description:
> > depot_tools: Ensure Python is bootstrapped before reading python3_bin_reldir.txt
> > 
> > Bug: 1017812
> > Change-Id: I7013e5445ff5917fab813a54fed416d9770d2684
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1913269
> > Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
> > Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> 
> TBR=dpranke@chromium.org,ehmaldonado@chromium.org,apolito@google.com
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 1017812
> Change-Id: I8e10894a2e835c20ece7d555c21f6ce1f76528a5
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1922949
> Reviewed-by: John Budorick <jbudorick@chromium.org>
> Commit-Queue: John Budorick <jbudorick@chromium.org>

Bug: 1017812
Change-Id: I251c6b1a3e3a7b9ac9d21dabe745466c668a8246
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1924494Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>