Fix log noise: cache_discovery=False for Gmail API, suppress aioimaplib INFO logs

Agent-Logs-Url: https://github.com/christianlouis/InboxConverge/sessions/8855bf16-124d-4d85-b6bd-ab82e8361114

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

backend/app/services/gmail_service.py

@@ -84,7 +84,9 @@ class GmailService:
     def service(self):
         """Lazy-initialize the Gmail API service."""
         if self._service is None:
-            self._service = build("gmail", "v1", credentials=self.credentials)
+            self._service = build(
+                "gmail", "v1", credentials=self.credentials, cache_discovery=False
+            )
         return self._service
 
     async def inject_email(