fix(docs): scope vitest run to target dir in js-libs-update workflow (#44943)

Vitest 4 no longer restricts test execution when a file path is passed
as a positional filter, causing all docs tests to run and fail on
unrelated tests. Use --dir to scope to the target directory. PR #44833
made the update which broke the behaviour.

.github/workflows/docs-js-libs-update.yml

@@ -55,7 +55,7 @@ jobs:
         working-directory: apps/docs
         run: |
           echo "Generating new typespec snapshot for review..."
-          npx vitest run --update ./features/docs/Reference.typeSpec.test.ts
+          npx vitest run --update --dir features/docs
 
       - name: Generate token
         id: app-token