This allows to keep only specific rules in derived rtags and to look for other
in the "parent" rtag, so that rules which are set there after the derived rtag
have been constructed are still considered (if not overriden).

This will avoid some rules duplication in at least the saem_ref cube. There may
be a few ones that may be removed from this cube but this is not done by this
commit.

Using this feature requires backporting fixes done in unreleased cubicweb
3.25.3.

Related to #17106806