Patch failures in bot_update return exit code 87 and 88, which are
ignored by ensure_checkout. This causes the bot_update step in recipes
to be successful despite a patch failure. This change removes these exit
codes from the accepted return codes for this step.

Bug: 1207685
Change-Id: I7bd71732a99184c96196659c6953e4d4b610c9b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2893686Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Gavin Mak <gavinmak@google.com>