This logic's predecessor, run_presubmit, used an 8-minute timeout in
all cases other than luci-py. Using that as a default (rather than 0s)
seems reasonable.

Recipe-Nontrivial-Roll: build
Change-Id: I4b8668531db1a243709979b580c5170c22a0729f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2020987
Commit-Queue: John Budorick <jbudorick@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>