### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

`PORTS_CHECK_DOCKER_IMAGE` is not configurable which prevents ECS tasks from running on air-gapped environment



### Expected Behavior

`PORTS_CHECK_DOCKER_IMAGE` can be configured via configuration option to allow use of any available image 

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

Run an ECS task in an environment where localstack/localstack is not available.

### Environment

```markdown
- OS: RHEL8
- Docker runtime version: Podman v4.2.0
- LocalStack: 1.3.1
```


### Anything else?

_No response_
"OUTBOUND_HTTP_PROXY",
    "OUTBOUND_HTTPS_PROXY",
    "PERSISTENCE",
    "REQUESTS_CA_BUNDLE",
    "S3_SKIP_SIGNATURE_VALIDATION",
    "S3_SKIP_KMS_KEY_VALIDATION",
    "SERVICES",
    "SKIP_INFRA_DOWNLOADS",
    "SKIP_SSL_CERT_DOWNLOAD",
    "SQS_DELAY_PURGE_RETRY",
    "SQS_DELAY_RECENTLY_DELETED",
    "SQS_ENDPOINT_STRATEGY",
    "SQS_PORT_EXTERNAL",
    "STEPFUNCTIONS_LAMBDA_ENDPOINT",
    "SYNCHRONOUS_KINESIS_EVENTS",
    "SYNCHRONOUS_SNS_EVENTS",
    "TEST_AWS_ACCOUNT_ID",
    "TEST_IAM_USER_ID",
    "TEST_IAM_USER_NAME",
    "TF_COMPAT_MODE",
    "THUNDRA_APIKEY",
    "THUNDRA_AGENT_JAVA_VERSION",
    "THUNDRA_AGENT_NODE_VERSION",
    "THUNDRA_AGENT_PYTHON_VERSION",
    "USE_SINGLE_REGION",
    "USE_SSL",
    "WAIT_FOR_DEBUGGER",
    "WINDOWS_DOCKER_MOUNT_PREFIX",
]
def is_local_test_mode() -> bool: