test(performance): skip every test-only file suffix in the zoneless guard

#1813 added serial-details.test-stubs.ts, whose stub components set
ChangeDetectionStrategy.Eager. The zoneless checklist guard listed only
some test-only suffixes, counted the stub file as production code and has
failed the performance-harness job on master since. It now skips every
`.spec` / `.test` file with or without a suffix, test-setup.ts and
test-stubs/ directories.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/architecture/zoneless-migration.md

@@ -153,8 +153,10 @@ files that still contain `ChangeDetectionStrategy.Eager`.
 - [ ] `libs/portal/xtream/feature/src/lib/global-search-results/global-search-results.component.ts`
 - [ ] `libs/portal/xtream/feature/src/lib/serial-details/serial-details.component.ts`
 
-Test stubs that set Eager (`*.spec.ts`, `*.spec-stubs.ts`, `*.spec-data.ts`,
-`*.test-helpers.ts`) are not listed; they do not ship.
+Test-only files that set Eager are not listed; they do not ship. The guard
+skips every `*.spec.ts` / `*.test.ts` file with or without a suffix
+(`*.spec-stubs.ts`, `*.test-helpers.ts`, `*.test-stubs.ts`, …),
+`test-setup.ts` and `test-stubs/` directories.
 
 ## Zone-dependent sites