CHROMIUM: test_initctl: Avoid testing non-guaranteed quiesce behavior

test_initctl has some mirrored tests for both "session" and "system"
shutdown. For the former, Upstart is more forgiving on timing deadlines,
and allows more jobs that "start on session-end" or similar to run [1].
This means we can expect 'session-end' jobs to complete, and to write
out their logs.

However for the latter, there is explicitly no such guarantee -- jobs
*may* run, but the quiesce timer may fire (racily) before the job runs
at all, let alone has time to write out its logs. This is especially
noticeable when we've shorten the timeouts down to the minimum, and run
tests under system load (so we're less likely to get lucky scheduling).

Thus, remove any expectation regarding log files for "system shutdown"
tests.

This resolves some test errors such as the following:

...system shutdown: one job which starts on session-end and ignores SIGTERM
BAD: wrong value for file, got unexpected (nil)
        at tests/test_initctl.c:11993 (test_quiesce).
FAIL test_initctl (exit status: 134)

[1] See a variety of comments in quiesce().

BUG=b:232122437
TEST=cros_run_unit_tests under system load

Change-Id: Ib32987b9e461e2c13f523219d710624b848ac762
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/upstart/+/5435499
Tested-by: Brian Norris <briannorris@chromium.org>
Commit-Queue: Brian Norris <briannorris@chromium.org>
Reviewed-by: Allen Webb <allenwebb@google.com>
1 file changed