controller_action_predispatch event executed in every action of Magento and the event you are talking about is dynamic that's why you are not able to find in the link which you have provided and in core Magento.
Not let's check your event
controller_action_predispatch_wishlist_index_remove in this event
controller_action_predispatch is static event name and
wishlist_index_remove is your action (I mean to remove item from the wishlist). Magento create this dynamic event on every action.
Just look in this line of
'controller_action_predispatch_' . $request->getFullActionName(),
You can see
controller_action_predispatch_ is statically written and
$request->getFullActionName() is dynamic. So in your case you are performing removing Item from wishlist so your full action name
wishlist_index_remove that's why your event name replace by