### 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_
LAMBDA_REMOTE_DOCKER = True
BUCKET_MARKER_LOCAL = (
    os.environ.get("BUCKET_MARKER_LOCAL", "").strip() or DEFAULT_BUCKET_MARKER_LOCAL
)
LAMBDA_DOCKER_NETWORK = os.environ.get("LAMBDA_DOCKER_NETWORK", "").strip()
LAMBDA_DOCKER_DNS = os.environ.get("LAMBDA_DOCKER_DNS", "").strip()
LAMBDA_DOCKER_FLAGS = os.environ.get("LAMBDA_DOCKER_FLAGS", "").strip()
LAMBDA_CONTAINER_REGISTRY = (
    os.environ.get("LAMBDA_CONTAINER_REGISTRY", "").strip() or DEFAULT_LAMBDA_CONTAINER_REGISTRY
)
LAMBDA_REMOVE_CONTAINERS = (
    os.environ.get("LAMBDA_REMOVE_CONTAINERS", "").lower().strip() not in FALSE_STRINGS
)
LOCAL_PORT_STEPFUNCTIONS = int(os.environ.get("LOCAL_PORT_STEPFUNCTIONS") or 8083)
STEPFUNCTIONS_LAMBDA_ENDPOINT = os.environ.get("STEPFUNCTIONS_LAMBDA_ENDPOINT", "").strip()
WINDOWS_DOCKER_MOUNT_PREFIX = os.environ.get("WINDOWS_DOCKER_MOUNT_PREFIX", "/host_mnt")
S3_SKIP_SIGNATURE_VALIDATION = is_env_not_false("S3_SKIP_SIGNATURE_VALIDATION")
TEST_IAM_USER_ID = str(os.environ.get("TEST_IAM_USER_ID") or "").strip()
TEST_IAM_USER_NAME = str(os.environ.get("TEST_IAM_USER_NAME") or "").strip()
LAMBDA_EXECUTOR = os.environ.get("LAMBDA_EXECUTOR", "").strip()
LAMBDA_FALLBACK_URL = os.environ.get("LAMBDA_FALLBACK_URL", "").strip()
LAMBDA_FORWARD_URL = os.environ.get("LAMBDA_FORWARD_URL", "").strip()
LAMBDA_CODE_EXTRACT_TIME = int(os.environ.get("LAMBDA_CODE_EXTRACT_TIME") or 25)
LAMBDA_STAY_OPEN_MODE = is_in_docker and is_env_not_false("LAMBDA_STAY_OPEN_MODE")
LAMBDA_TRUNCATE_STDOUT = int(os.getenv("LAMBDA_TRUNCATE_STDOUT") or 2000)
KINESIS_INITIALIZE_STREAMS = os.environ.get("KINESIS_INITIALIZE_STREAMS", "").strip()
OPENSEARCH_CUSTOM_BACKEND = (
    os.environ.get("OPENSEARCH_CUSTOM_BACKEND", "").strip()
    or os.environ.get("ES_CUSTOM_BACKEND", "").strip()
)