Autotest: Setting tst_qaudiooutput and tst_qsound as insignificant

These always fails on virtual Mac CI nodes.

Task-number: QTBUG-43507
Change-Id: I8f8fab92693aea7c797eee4e930c8ed5e82954c9
Reviewed-by: Akseli Salovaara <akseli.salovaara@digia.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>