I noticed that chromium/src archive grew 2x from 7.3GiB in August
to 15+ GiB now. Turns out --aggressive-gc had no effect.

R=iannucci

Change-Id: I6a27f67f5a4dd2101ac1622221106e094af4688a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1928583
Auto-Submit: Andrii Shyshkalov <tandrii@google.com>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>