Follow review comments

e2e_tests/utils.py

@@ -1,9 +1,20 @@
 from optuna_dashboard._storage import trials_cache
 from optuna_dashboard._storage import trials_cache_lock
 from optuna_dashboard._storage import trials_last_fetched_at
+from playwright.sync_api import Page
 
 
 def clear_inmemory_cache() -> None:
     with trials_cache_lock:
         trials_cache.clear()
         trials_last_fetched_at.clear()
+
+
+def count_components(page: Page, component_name: str):
+    component_count = page.evaluate(
+        f"""() => {{
+        const components = document.querySelectorAll('.{component_name}');
+        return components.length;
+    }}"""
+    )
+    return component_count