Backport of "rtprtx: don't access type-system per buffer" into 1.20
requested to merge tpm/gstreamer:backport-mr-1873-into-1.20-hgr-rtx-2-type-system-per-buffer into 1.20
Backport of !1873 (merged) "rtprtx: don't access type-system per buffer".
Commits:
- a475c933 rtprtx: don't access type-system per buffer