[starnix] Debounce container suspend

This is a short-term hack. Hardcode a timeout period for debouncing
suspends. This solves the problem of repeated suspend/resume cycles
before the system has a chance to do work.

See b/495092629 and b/494358771 for additional background.

Note that on patchset 1 we tried blocking suspend for the debounce
period which failed, so now for the debounce period we simply return
success immediately.

b/495092629 has a longer-term fix for this issue which debounces based
on runtime data instead of using a hardcoded value.

Tested: See data on b/495821937.
Bug: 494358771
Bug: 495092629
Fixed: 495821937
Change-Id: I916bdf15c3d17c951779ddadacac172f2ec20293
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1551571
Reviewed-by: Benjamin Lerman <qsr@google.com>
API-Review: Benjamin Lerman <qsr@google.com>
Commit-Queue: Brian Bosak <bbosak@google.com>