pipelines.json: add qtdemux reverse playback test
There was a bug, fixed by gst-plugins-good!275 (merged), where qtdemux would drop the entire last GOP in reverse playback (so in that test, the only GOP). Let's make sure we don't regress.
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There was a bug, fixed by gst-plugins-good!275 (merged), where qtdemux would drop the entire last GOP in reverse playback (so in that test, the only GOP). Let's make sure we don't regress.