There should be no functional change to users here unless they set
evil-collection-corfu-themes to something other than '(default).
It might be worth making this key-theme a global custom variable
evil-collection-key-themes instead and using a namespaced corfu symbol
instead. e.g. (defcustom evil-collection-key-themes '(corfu-default)) so that
users will only have to know one variable to customize.
