Doors: Disable client dig prediction for protected doors

mods/doors/init.lua

@@ -410,6 +410,7 @@ function doors.register(name, def)
 
 			return secret, "a locked door", owner
 		end
+		def.node_dig_prediction = ""
 	else
 		def.on_blast = function(pos, intensity)
 			minetest.remove_node(pos)