[uicfg] Fix autoform_section rtags wrt derivation
cw 3.25 introduced the 'derived rtags' feature, but missed that
`autoform_section` implementation was overriding several methods where this was
implemented in the base class. The following problems are tested and fixed:
* during init, we should not attempt to call `_initfunc_step2` if there is some
parent,
* but we should handle expansion of wildcard ('*' used as subject or object of a
tag) since this is handled during init step for this class, unlike others
which handle this in `get` method (i.e. at lookup time),
* fix overrided `get` method to consider parent rtag if any.
Closes #17107020