Add two additional E2E tests for unit testing support

[clydin]

• Adds an end-to-end test to verify that tslib is correctly resolved
  when using custom decorators within Vitest unit tests. This ensures
  compatibility with Angular decorators and the Vitest runner's module
  resolution configuration.
• Adds an end-to-end test to verify Vitest runner performance and correctness
  with a larger number of generated components, services, and pipes. This test
  executes the suite in both JSDOM and browser environments to ensure stability
  and proper functionality under scale.

[clydin]

This PR was merged into the repository. The changes were merged into the following branches:

• main: 960c80c
• 21.0.x: bb29254

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}