Fix a Py3 bug in presubmit_canned_checks.py.
Fix a Py3 bug in presubmit_canned_checks.py.

There were a couple of references to using filter() that
needed to be replaced with list comprehensions as the return
values may be used repeatedly.

Bug: 1207012
Change-Id: Iae0abd38aeb186d6f7945f8c848c1f7312cb45bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2890329
Reviewed-by: Edward Lesmes <d05609f027dc667cc37492b1dc1bdea5d60fa82a@chromium.org>
Commit-Queue: Dirk Pranke <6693ee08b084bb2ffa767f664c99b689395e0e4b@google.com>

CoherentLabs/depot_tools,CoherentLabs/depot_tools