linux: module: uninstall legacy modules on (un)installation

This can be reverted once we're sure nobody's using them anymore
(post-3.0 release?)

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13274