This reverts commit 5b6ae8bc.

Reason for revert: Suspected breakage of wpt-importer (https://ci.chromium.org/p/infra/builders/cron/wpt-importer)

Original change's description:
> git-cl: Use bb to schedule try jobs.
>
> Bug: 976104
> Change-Id: I3423667f1ed9edfc5fa17842932de7704951fc62
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1801799
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
> Reviewed-by: Andrii Shyshkalov <tandrii@google.com>

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

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 976104
Change-Id: I885c1e71b34928c402d3375f820b28f3d6535c54
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1806148Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>