Backport of "qtdemux: emit no-more-pads after pruning old pads" into 1.22
requested to merge tpm/gstreamer:backport-mr-4535-into-1.22-qtdemux-no-more-pads-after-prune into 1.22
Backport of !4535 (merged) "qtdemux: emit no-more-pads after pruning old pads".
Commits:
- 021572de qtdemux: emit no-more-pads after pruning old pads