RNA code to create new actions did not properly remove the extra user
set by default, as done in other `new` callbacks of other ID types.
NOTE: Mask ID had the same issue, also fixed in this commit.
NOTE: At some point this needs to be properly fixed, default super-low
level ID creation code should simply not add a 'default' user, this is
extremely bad design and forces higher-level code to do all kind of
extra work to get rid of it half of the time, in very unclear and
confusing ways and places.
6dd2e193e1