### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When attempting to sign some document using Localstack KMS inside a lambda container (also running on localstack), the localstack KMS listener returns some unknown error.

The KMS key and lambda containers have been created from the same CDK app deploy, and I can see all the resources in the localstack web console.

The test application I'm using to prove this behaviour is available here:
https://github.com/LukaHedt/localstack_kms_test

Instructions to run are in the main Readme, and the `/localstack/Readme.md` file.

`aws-sdk` returns an unknown error, and the localstack docker logs that I receive are available here:
https://pastebin.com/58Z3fXi3

Have done an amount of testing and can confidently claim the following:
- Have tested on multiple machines with the same outcome
- Doesn’t make a difference if I specify an ARN or a KeyID in the signing request
- Downgrading localstack versions either didn’t make a difference, or I couldn’t actually deploy a localstack container with version 0.12.20 or lower.

### Expected Behavior

KMS Sign should return a signature for the given payload.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

Test application demonstrating the current behaviour is available here:

https://github.com/LukaHedt/localstack_kms_test

Full instructions to run are in the `/localstack/Readme.md` file.


### Environment

```markdown
- OS: MacOS Monteray 12.3
- LocalStack: 0.14.0
```


### Anything else?

_No response_
"""Returns True if we are running in the context of our local integration tests."""
    return is_env_true(ENV_INTERNAL_TEST_RUN)
def collect_config_items() -> List[Tuple[str, Any]]:
    """Returns a list of key-value tuples of LocalStack configuration values."""
    none = object()  
    
    keys = []
    keys.extend(CONFIG_ENV_VARS)
    keys.append("DATA_DIR")
    keys.sort()
    values = globals()
    result = []
    for k in keys:
        v = values.get(k, none)
        if v is none:
            continue
        result.append((k, v))
    result.sort()
    return result
def parse_service_ports() -> Dict[str, int]: