pbutils: fix visualization plugins
Noticed when I upgraded to Fedora 40 which included 1.22.12, and the visualization plugins either started immediately crashing (synaescope) or misrendering and eventually crashing (all others). Tracked it down to being introduced in !6320 (merged)
inbuf is persistent, GST_BUFFER_COPY_MEMORY's append behavior is not what we want here.
I'm not an expert, but moving back to the prior behavior (gst_buffer_replace_all_memory) fixes it for me.
If this is correct, it needs backported to 1.22 and 1.24.