Add tests for DBZ-2617: PG connector does not enter FAILED state on failing heartbeats

Add tests for DBZ-2617: Postgres connector does not enter FAILED state on failing heartbeats when Postgres is shutdown with shutdown mode `fast` and PG is also not able to shutdown while the connector is streaming.

We need to add integration tests for the fix provided in DBZ-2617. For this we need to enable Testcontainers in Postgres Connector tests.