[PendingFileQueueTest] Shorten timeouts, verify tracking time

Summary:
There is no need to wait 2 seconds until the file is processed from the
pending file queue.

Check if the file is removed from the recently emitted queue after the
set tracking time has elapsed.

Depends on D21790 to remove the timeout jitter

Test Plan: ctest

Reviewers: Baloo, ngraham, astippich, poboiko

Reviewed By: Baloo, ngraham

Subscribers: kde-frameworks-devel

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D21791