Since we updated the devkit dependencies, we need to update
the browserslist DB versions in integration tests to avoid
browser mismatches causing errors like the following:
```
BrowserslistError: [BABEL] /tmp/ng-integration-test-91jP3g/test-sandbox/node_modules/zone.js/fesm2015/zone.js: Unknown version 114 of edge (While processing: "base$0$0")
```
PR Close#50772
Since v15, prod mode is handled by the CLI with the `optimization` flag. We can remove the environement files and `enableProdMode` when the tests use the CLI.
PR Close#49746
The Testability-related logic was refactored in https://github.com/angular/angular/pull/45657 to become tree-shaking-friendly: it was decoupled from the core providers of the `BrowserModule`. This commit updates the newly-introduced `bootstrapApplication` function to exclude Testability-providers by default (note: the Testability is still included in the NgModule-based bootstrap).
In order to add the Testability to the app bootstrapped via `bootstrapApplication`, the `provideProtractorTestingSupport` function is introduced.
PR Close#45885
This commit adds 2 integration apps to verify the `bootstrapApplication` API behavior as well as keep track of the bundle size and retained symbols (tree-shaking).
PR Close#45674
