In version 12.1, the framework added the `destroyAfterEach` an opt-in feature that improves tests performance and also addresses two long-standing issues.
The idea, is to have this enabled by default in the future. Related PR: https://github.com/angular/angular/pull/42566Closes#21280
The supported versions of Node.js support up to ES2018, the only reason why we don't use ES2017+ is because native `async` and `await` don't work with zone.js
See: https://github.com/angular/angular/issues/31730
With this change, we also ensure that we don't downlevel the server bundle to ES5 which is unnecessary.
Closes: #17794