Backport of "splitmuxsink: always use factory property when set" into 1.18
requested to merge tpm/gst-plugins-good:backport-mr-1024-into-1.18-splitmuxsink-fix-muxer-factory into 1.18
Backport of !1024 (merged) "splitmuxsink: always use factory property when set".
Commits:
- a6d6e99f splitmuxsink: always use factory property when set