fix: improve OpenGauss detection to correctly disable UNLISTEN

The previous detection logic was insufficient for standard OpenGauss environments (e.g., A-compatibility or default modes) as it relied on keys like 'sql_mode' which may not exist.

Changes:
1. Updated `_detect_server_capabilities` to identify GaussDB/OpenGauss using the core parameter `session_respool`.

Author: zhanghaitao3

async_gaussdb/connection.py

@@ -2647,8 +2647,6 @@ class _ConnectionProxy:
 
 
 def _detect_server_capabilities(server_version, connection_settings):
-    print(connection_settings)
-    print(server_version)
     if hasattr(connection_settings, 'padb_revision'):
         # Amazon Redshift detected.
         advisory_locks = False