SIENTIAPDE-994

Refactor tests for Postgres activities and improve error handling

- Updated test_postgres.py to enhance the testing of load_custom_query method, including cases for None data and date conversion.
- Refactored repeat_last_prediction tests to use mocks for SQLAlchemy session execution.
- Added tests for export_data_to_postgres method, covering both success and error scenarios.
- Improved the initialization tests for Activities class to ensure proper instantiation of dependencies.
- Enhanced test coverage for OPC repository connection validation.
- Updated tests for prediction workflows to streamline input handling and improve clarity.
- Introduced tests for connectors configuration to validate environment variable handling for MLFlow, OPC, and Postgres.
- Added tests for logger utility to ensure default settings are correctly applied.

laborious/utils/repository/opc_repository.py

@@ -122,12 +122,17 @@ class OpcRepository():
             return False
 
     def disconnect(self):
+        if self.client is None:
+            return
         self.client.disconnect()
         self.client = None
         self.logger.info('Disconnected from OPC server')
 
     def __del__(self):
-        self.disconnect()
+        try:
+            self.disconnect()
+        except Exception as e:
+            self.logger.error(f"Error in destructor: {e}")
 
     def validate_connection(self):
         if self.client is None: