Fix bug in ThreadPoolImplTest.UpdatePrioritySequenceNotScheduled_PreferBackground

This patch fixes a bug in
ThreadPoolImplTest.UpdatePrioritySequenceNotScheduled_PreferBackground
gtest that makes test expectations incorrect when testing task
scheduling with the feature kUseUtilityThreadGroup enabled.

This replaces the condition CanUseBackgroundThreadTypeForWorkerThread
with a check that also uses test->GetUseResourceEfficientThreadGroup()
as the former does not check the full conditions under which the tasks
might not be run in-order.

The bug caused the test to assume that two tasks where executed in-order
which might not be the case when using utility thread group. The test
still passed most of the time on most systems, but on slower systems
this race condition can be seen more often.

Change-Id: I7c8acb506e7c2b7bae42f3c4ec87c90e526585e0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4865688
Reviewed-by: Etienne Pierre-Doray <etiennep@chromium.org>
Commit-Queue: Hans-Filip Elo <hans-filip.elo@xperi.com>
Cr-Commit-Position: refs/heads/main@{#1197100}