refactor(docs-infra): fix docs examples for tslint rule only-arrow-functions (#38143)

This commit updates the docs examples to be compatible with the
`only-arrow-functions` tslint rule.

This is in preparation of updating the docs examples `tslint.json` to
match the one generated for new Angular CLI apps in a future commit.

PR Close #38143

aio/content/examples/lazy-loading-ngmodules/e2e/src/app.e2e-spec.ts

@@ -18,24 +18,24 @@ describe('providers App', () => {
     expect(page.getTitleText()).toEqual('Lazy loading feature modules');
   });
 
-  describe('Customers', function() {
-    beforeEach(function() {
+  describe('Customers', () => {
+    beforeEach(() => {
       customersButton.click();
     });
 
-    it('should show customers when the button is clicked', function() {
+    it('should show customers when the button is clicked', () => {
         let customersMessage = element(by.css('app-customers > p'));
         expect(customersMessage.getText()).toBe('customers works!');
     });
 
   });
 
-  describe('Orders', function() {
-    beforeEach(function() {
+  describe('Orders', () => {
+    beforeEach(() => {
       ordersButton.click();
     });
 
-    it('should show orders when the button is clicked', function() {
+    it('should show orders when the button is clicked', () => {
         let ordersMessage = element(by.css('app-orders > p'));
         expect(ordersMessage.getText()).toBe('orders works!');
     });