I had in the product edit page only because it was easier to test there
while i was developing it, but it is something that should be done for
all select[multiple], of course.
I removed the whole x-cloak thing because i am not sure what would
happen if i do something wrong and Alpine can not initialize the
multiselect; probably show nothing to the user. Now it shows the
native select a fraction of a second, but if i fuck it up at least the
user can still use the app.