Code was often referring to pie menus using the term "radial" which just
obfuscates that it relates to pie menus. Just call it what it is
directly.
Doesn't replace usages of the term for names that are not strictly tied
to pie menus. Also doesn't change instances of the term in the Python
API to keep compatibility, noted in #110461.
Pull Request: https://projects.blender.org/blender/blender/pulls/122825
e425faf696