docs(unit-testing): move afterAll() to the end

in the example of e2e testing with Fastify

Author: DanielKucal

content/fundamentals/unit-testing.md

@@ -287,10 +287,6 @@ describe('Cats', () => {
 >   await app.init();
 >   await app.getHttpAdapter().getInstance().ready();
 > });
-> 
-> afterAll(async () => {
->   await app.close();
-> });
 >
 > it(`/GET cats`, () => {
 >   return app
@@ -303,6 +299,10 @@ describe('Cats', () => {
 >       expect(result.payload).toEqual(/* expectedPayload */);
 >     });
 > });
+>  
+> afterAll(async () => {
+>   await app.close();
+> });
 > ```
 
 In this example, we build on some of the concepts described earlier. In addition to the `compile()` method we used earlier, we now use the `createNestApplication()` method to instantiate a full Nest runtime environment. We save a reference to the running app in our `app` variable so we can use it to simulate HTTP requests.