[DAG] Ensure extract_subvector(insert_subvector(x,y,c1),c2) -->...

[DAG] Ensure extract_subvector(insert_subvector(x,y,c1),c2) --> extract_subvector(y,c2-c1) is working on fixed vector types

#87925 failed to ensure we weren't removing the extracted subvector from a scalable vector type

Thanks to @antmox for the headsup.