### 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_
LEGACY_DOCKER_CLIENT = is_env_true("LEGACY_DOCKER_CLIENT")
FORWARD_EDGE_INMEM = True
EDGE_BIND_HOST = os.environ.get("EDGE_BIND_HOST", "").strip() or "127.0.0.1"
EDGE_PORT = int(os.environ.get("EDGE_PORT") or 0) or DEFAULT_PORT_EDGE
EDGE_PORT_HTTP = int(os.environ.get("EDGE_PORT_HTTP") or 0)
EDGE_FORWARD_URL = os.environ.get("EDGE_FORWARD_URL", "").strip()
DOCKER_BRIDGE_IP = os.environ.get("DOCKER_BRIDGE_IP", "").strip()
ENABLE_CONFIG_UPDATES = is_env_true("ENABLE_CONFIG_UPDATES")
DISABLE_CORS_CHECKS = is_env_true("DISABLE_CORS_CHECKS")
DISABLE_CUSTOM_CORS_S3 = is_env_true("DISABLE_CUSTOM_CORS_S3")
DISABLE_CUSTOM_CORS_APIGATEWAY = is_env_true("DISABLE_CUSTOM_CORS_APIGATEWAY")
EXTRA_CORS_ALLOWED_HEADERS = os.environ.get("EXTRA_CORS_ALLOWED_HEADERS", "").strip()
EXTRA_CORS_EXPOSE_HEADERS = os.environ.get("EXTRA_CORS_EXPOSE_HEADERS", "").strip()
EXTRA_CORS_ALLOWED_ORIGINS = os.environ.get("EXTRA_CORS_ALLOWED_ORIGINS", "").strip()
DISABLE_EVENTS = is_env_true("DISABLE_EVENTS")
DEBUG_ANALYTICS = is_env_true("DEBUG_ANALYTICS")
EAGER_SERVICE_LOADING = is_env_true("EAGER_SERVICE_LOADING")
SKIP_INFRA_DOWNLOADS = os.environ.get("SKIP_INFRA_DOWNLOADS", "").strip()
SKIP_SSL_CERT_DOWNLOAD = is_env_true("SKIP_SSL_CERT_DOWNLOAD")
LEGACY_PERSISTENCE = is_env_not_false("LEGACY_PERSISTENCE")
MAIN_CONTAINER_NAME = os.environ.get("MAIN_CONTAINER_NAME", "").strip() or "localstack_main"
LOCALSTACK_BUILD_GIT_HASH = os.environ.get("LOCALSTACK_BUILD_GIT_HASH", "").strip() or None
LOCALSTACK_BUILD_DATE = os.environ.get("LOCALSTACK_BUILD_DATE", "").strip() or None
OUTBOUND_HTTP_PROXY = os.environ.get("OUTBOUND_HTTP_PROXY", "")
OUTBOUND_HTTPS_PROXY = os.environ.get("OUTBOUND_HTTPS_PROXY", "")
ARN_PARTITION_REWRITING = is_env_true("ARN_PARTITION_REWRITING")
FORCE_SHUTDOWN = is_env_not_false("FORCE_SHUTDOWN")
MOCK_UNIMPLEMENTED = is_env_true("MOCK_UNIMPLEMENTED")
no_proxy = ",".join([LOCALSTACK_HOSTNAME, LOCALHOST, LOCALHOST_IP, "[::1]"])
if os.environ.get("no_proxy"):