Make test_deferred_delete() be deterministic

This makes the test_deferred_delete test deterministic in its
execution. Since it depends on periodic task scheduling and
a somewhat unknown amount of time before the state change
polling loop will give up, it has been failing a lot lately.

This enforces a run of the specific task needed, as well as
ensures that time appears to have elapsed sufficiently to
justify a reclaim.

Fixes bug 1193167

Change-Id: Ideaf8abd19b10e018d284085309fe63282fa4b82
Merge "Make test_deferred_delete() be deterministic"