Move study body back to fn_selfActions

Adding UserActions to players (CAManBase) is not efficient, because the
condition evaluates onEachFrame when you are "inside" that vehicle type.
Also admins usually want to add more custom actions to dead bodies
anyway.
https://community.bistudio.com/wiki/addAction#Syntax

This partially reverts 3aad4b6.

SQF/dayz_code/Configs/CfgVehicles/Zeds/Zeds.hpp

@@ -73,7 +73,6 @@ class zZombie_Base : Zed_Base {
 			condition = "(['Butcher',this] call userActionConditions)";
 			statement = "this spawn player_butcher;";
 		};
-		delete StudyBody;
 	};
 	
 	class HitPoints {