When we destroy the document without LOK we leak the LOK Notifier
subsystem, which doesn't get destroyed, since LOK is inavtive by
then.

Though it's not entirely clear why only this test suffered this
issue, I avoided making unwarranted changes without reason
(i.e. failing tests).

Change-Id: Ib098b8ff3c828cb94a55d1f8cd1f0b010240a749