fix(@angular/build): use dynamic TestComponentRenderer for Vitest

This commit implements a custom TestComponentRenderer in the virtual init-testbed.js file generated for Vitest. In Vitests non-isolated mode (isolate: false) with JSDOM, Vitest creates a fresh document for each spec file but reuses the module cache. The default Angular DOMTestComponentRenderer caches the document during initialization, leading to stale references and errors like setAttribute is not a function in subsequent tests. The new DynamicDOMTestComponentRenderer looks up the document dynamically on every operation, resolving the issue without requiring a breaking change to defaults or affecting browser-based testing.