`sock_rotation` has higher priority (6) than the vector socket (4).
Hence inserting node between vector-vector link joins thorugh "rotation"
socket (`get_main_socket()` / `get_main_socket_priority()`).
This can be fixed by making "vector" input socket as default for link.
But this will break the link creation when node is inserted between
rotation-rotation link. It seems rotation is converted to vectors so
perhaps make sense to make "vector" as default socket for link.
Pull Request: https://projects.blender.org/blender/blender/pulls/116550
5f70bd0e46