[gnome-42] RDP/VNC: Ensure PipeWire buffers to be queued before destroying them
Cherry-pick to gnome-42 branch !178 (merged) and !182 (merged).
This is useful for Ubuntu LTS, but I guess can be merged upstream too.
/cc @jbicha handles https://bugs.launchpad.net/ubuntu/+source/gnome-remote-desktop/+bug/2024238 and https://bugs.launchpad.net/ubuntu/+source/gnome-remote-desktop/+bug/2024240