fix(embedded-e2e): address round-2 review findings

- Gate chromium-embedded project on INCLUDE_EMBEDDED env var; set only in
  superset-playwright.yml (shadow mode) so it never runs in required E2E
- Add embedded test step to experimental workflow alongside experimental step
- Remove SUPERSET_FEATURE_EMBEDDED_SUPERSET from required workflow (no longer needed)
- Remove dead CORS_OPTIONS from superset_test_config (helpers bypass CORS via page.request)
- Log teardown errors in afterAll instead of swallowing with bare catch {}
- Wrap allowed_domains restore in its own try/catch so it can't mask assertion failures
- Gate TALISMAN_ENABLED + PUBLIC_ROLE_LIKE in docker_light behind SUPERSET_FEATURE_EMBEDDED_SUPERSET
- Add failOnStatusCode:true to guest_token request so silent 4xx surfaces immediately
- Remove dead window.__guestToken fallback branch from embedded test app

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/superset-e2e.yml

@@ -169,7 +169,6 @@ jobs:
       PYTHONPATH: ${{ github.workspace }}
       REDIS_PORT: 16379
       GITHUB_TOKEN: ${{ github.token }}
-      SUPERSET_FEATURE_EMBEDDED_SUPERSET: "true"
     services:
       postgres:
         image: postgres:17-alpine

.github/workflows/superset-playwright.yml

@@ -44,6 +44,7 @@ jobs:
       REDIS_PORT: 16379
       GITHUB_TOKEN: ${{ github.token }}
       SUPERSET_FEATURE_EMBEDDED_SUPERSET: "true"
+      INCLUDE_EMBEDDED: "true"
     services:
       postgres:
         image: postgres:17-alpine
@@ -131,6 +132,13 @@ jobs:
           NODE_OPTIONS: "--max-old-space-size=4096"
         with:
           run: playwright-run "${{ matrix.app_root }}" experimental/
+      - name: Run Playwright (Embedded Tests)
+        if: steps.check.outputs.python || steps.check.outputs.frontend
+        uses: ./.github/actions/cached-dependencies
+        env:
+          NODE_OPTIONS: "--max-old-space-size=4096"
+        with:
+          run: playwright-run "${{ matrix.app_root }}" embedded
       - name: Set safe app root
         if: failure()
         id: set-safe-app-root