[BUG] RDS Aurora autodiscovery doesn't work when using Docker labels to configure it

[public]

Agent Environment
Version: 7.57.1

Running in an ECS container in EC2.

Describe what happened:

The documentation describes autodiscovery working with Aurora based on AWS tags and that it can be configured using Docker labels.

https://docs.datadoghq.com/database_monitoring/guide/aurora_autodiscovery/?tab=postgres
https://docs.datadoghq.com/containers/docker/integrations/?tab=labels

Doing this results in no errors being reported by the agent, but also it doesn't actually do any autodiscovery and it does not connect to the databases.

Here is my label configuration.

com.datadoghq.ad.checks: '{
  "postgres":
    {
      "ad_identifiers": [
        "_dbm_postgres_aurora"
      ],
      "instances": [
        {
          "host": "%%host%%",
          "port": "%%port%%",
          "username": "datadog",
          "dbm": true,
          "aws": {
            "instance_endpoint": "%%host%%",
            "region": "%%extra_region%%",
            "managed_authentication": {
              "enabled": "%%extra_managed_authentication_enabled%%"
            }
          },
          "tags": [
            "dbclusteridentifier:%%extra_dbclusteridentifier%%",
            "region:%%extra_region%%"
          ]
        }
      ]
    }
  }'

Disabling managed_authentication has no effect.

Describe what you expected:

I expected to be able to provide the autodiscovery information via Docker labels and that it would discover my tagged AWS Aurora clusters automatically and try to connect to them.

Steps to reproduce the issue:

Follow the documentation.

Additional environment details (Operating System, Cloud provider, etc):

The agent is running inside an ECS container. This works fine for normal monitoring and also works fine for non-autodiscovery integration for database monitoring via Docker labels configuration. i.e. if I manually specify every DB to connect to it works and reports metrics just fine.