CFTL registers a help screen via a deprecated API

[benlk]

contextual_help is deprecated since version 3.3.0! Use get_current_screen()->add_help_tab(), get_current_screen()->remove_help_tab() instead.

https://github.com/INN/largo/blob/590181982d22a5444eb3c5ccca58ea8b56db12f7/inc/wp-taxonomy-landing/functions/cftl-admin.php#L185-L200

This is low-priority if we're eliminating CFTL; medium-priority otherwise.