Fix api-registry to fetch all services

- API Registry no longer supports enabling apis. To get all the apis, one needs to pass additional filter to fetch the apis. This allows the library to fetch all available apis.

Author: Prem Ramanathan

src/google/adk/integrations/api_registry/api_registry.py

@@ -61,7 +61,10 @@ def __init__(
       page_token = None
       with httpx.Client() as client:
         while True:
-          params = {}
+          params = {
+            # Include all the apis including disabled ones. API registry no longer supports enabling APIs.
+            "filter": "enabled=false"
+          }
           if page_token:
             params["pageToken"] = page_token