Tests: Add label 'media-backend' to test that exercise a media backend


This allows us to run subsets of the tests based on this property.
Useful for incoming CI changes.

Pick-to: 6.12
Change-Id: I957c98fd8f91b3e2fc72d0790c4b9676ca74f5e3
Reviewed-by: Tim Blechmann <tim.blechmann@qt.io>
commit1ebedad1437717e92dceec931b68ef7870e47fcc
parent68e09b707ba5d64f7e924f52199f83e975525f22
authorNils Petter Skålerud <nils.petter.skalerud@qt.io>
committerNils Petter Skålerud <nils.petter.skalerud@qt.io>
commit timeWed, 14 Oct 2026 09:36:33 +0000