- upstream libuavcan was broken and then marked deprecated, this fully absorbs the submodule (renamed libdronecan to deconflict) up to our last good working commit and all commit history is kept
- fixes https://github.com/PX4/PX4-Autopilot/issues/23727 (regression introduced in #23113)
- this puts us in a much better position to evolve the library as needed now that we have full control