Clean up defcustom type quote check

Clean up defcustom type quote check

* lisp/emacs-lisp/bytecomp.el
(byte-compile--suspicious-defcustom-choice): Rename to...
(byte-compile--defcustom-type-quoted): ...this and rewrite to make
more sense.  All callers updated.
(byte-compile-nogroup-warn): Better warning message.
* test/lisp/emacs-lisp/bytecomp-tests.el
(test-bytecomp-defgroup-choice): This never failed because it wasn't
actually a test.  Turn it into...
(bytecomp-test-defcustom-type-quoted): ...this, which is.