[autotests] In internal window test remove spy waits or guard them

Summary:
The internal window test is failing on CI because the client add spy waits
are not triggered. The signal has been emitted already at this point.

Removing them fixes this (the condition is still checked by subsequent
count verify on the spy) in all but one instance. In this case the wait
needs to be guarded.

Is there a more general approach to it? Always guarding is ugly. Also when
was this test regression introduced? In the past we must have had some
slack until the signal was fired to start the wait call.

Test Plan: Internal window test passes with this patch again.

Reviewers: #kwin, zzag

Reviewed By: #kwin, zzag

Subscribers: davidedmundson, zzag, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D22119