Child `GenerateStaticParams` Returning Empty Array For Some Parent Params Causes All Static Params To Be Dropped

In Next.js's `collectGenerateParams` (packages/next/src/build/utils.ts), the build process prematurely returns an empty result for an entire dynamic segment when a child `generateStaticParams` returns `[]` for a specific parent parameter combination. This early bail-out does not continue iterating over other parent parameter sets, so valid static entries from sibling parent values are lost.

1. Create a parent dynamic segment `[lang]` whose layout `generateStaticParams` returns `[{ lang: 'en' }, { lang: 'fr' }]`. 2. Create a child dynamic segment `[slug]` whose page `generateStaticParams` returns non-empty slugs for 'en' and `[]` for 'fr'. 3. Create a control child route that returns non-empty slugs for both parents. 4. Run `next build` and observe that the bug route produces zero HTML files while the control route produces four.

This patch changes the behavior for routes that intentionally return an empty array from `generateStaticParams` at the top level to opt out of static generation entirely. Such routes may now be treated as dynamic rather than producing zero static pages. Test dynamic fallback, catch-all routes, and cases where all parent combinations return empty to ensure no unintended changes. Rollback: keep a backup of the original `collectGenerateParams` function and revert if dynamic rendering behavior regresses.