Implement pg8000 graceful shutdown and error handling for database connection error

**Summary**

Implement graceful shutdown and improved error handling for pg8000 database connections using setup_pg8000_close_event_listener from the Cloud SQL Python Connector to reduce connection‑related errors and improve application reliability.

**Background**

The application is currently experiencing frequent pg8000 database connection errors, indicating that connections are not being properly closed or managed during:

- Application shutdown

- Container lifecycle events (Cloud Run)

- Transient failures or restarts

**Proposed Solution**

Implement proper connection lifecycle management in each application (as identified in logs) by:

https://github.com/bcgov/sbc-connect-common/blob/main/python/cloud-sql-connector/src/cloud_sql_connector/connector.py#L150

Ensuring:

- Database connections are gracefully closed on application/container shutdown

- Errors are handled explicitly (retry/backoff where appropriate)

- Connection handling aligns with Cloud Run lifecycle best practices

## Acceptance Criteria

- [ ] As a first step, please identify all applications that may be impacted, based on the issues identified in the logs or Error report from GCP Monitor.