refactor(docs-infra): remove unnecessary use strict from docs examples TS files (#38143)

By default, TypeScript will emit `"use strict"` directives, so it is not
necessary to include `'use strict'` in `.ts` files:
https://www.typescriptlang.org/docs/handbook/compiler-options.html#:~:text=--noImplicitUseStrict

PR Close #38143

aio/content/examples/built-in-directives/e2e/src/app.e2e-spec.ts

@@ -1,5 +1,3 @@
-'use strict';
-
 import { browser, element, by } from 'protractor';
 
 describe('Built-in Directives', function () {