fix: address codex review for PR3 (async)

- Fix SVS client leak in async_planner check_svs_requirements
- Remove dead async_utils.py (functions duplicated in async_executor)

Author: nkanu17

redisvl/migration/async_planner.py

@@ -161,13 +161,15 @@ async def _check_svs_vamana_requirements(
             return warnings
 
         # Check Redis version support
+        created_client = False
         try:
             if redis_client:
                 client = redis_client
             elif redis_url:
                 from redis.asyncio import Redis
 
                 client = Redis.from_url(redis_url)
+                created_client = True
             else:
                 client = None
 
@@ -182,6 +184,9 @@ async def _check_svs_vamana_requirements(
                 "SVS-VAMANA requires Redis >= 8.2.0 and Redis Search >= 2.8.10. "
                 "Verify your Redis instance supports this algorithm before applying."
             )
+        finally:
+            if created_client and client is not None:
+                await client.aclose()  # type: ignore[union-attr]
 
         # Intel hardware warning for compression
         if uses_compression: