Prior to this change, both taxonomies and post types added meta boxes to the Menus UI (which in-turn registered screen options) using the same ID formula: `add-{$id}`. This caused a conflict between the two elements, resulting in the rendering of a screen option for only the taxonomy or post type but not both. Moving to a new meta box ID for post types, `add-post-type-{$id}`, removes that conflict.
Note: This change in meta box IDs for post types effectively resets current user settings for the visibility of post types in the Menus UI.
Fixes#33925.
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