Why are there no hole in the ozone layer when spacecrafts leave the ozone layer?

The ozone layer is just a layer of gas, so while the ozone might get "stirred up" a bit, it does not form a hole. An ozone hole is not a physical hole; it's only an area in the ozone layer where the ozone levels are very low because of decomposition by chemicals.
Consider this: If you move your hand through the air, does it leave a vacuum behind? No. The air around it fills in the space almost instantly. Same thing with the spacecraft going through the ozone layer.