### 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_
response = Response()
            response.status_code = 200
            self._table_ttl_map[data["TableName"]] = {
                "AttributeName": data["TimeToLiveSpecification"]["AttributeName"],
                "Status": data["TimeToLiveSpecification"]["Enabled"],
            }
            response._content = json.dumps(
                {"TimeToLiveSpecification": data["TimeToLiveSpecification"]}
            )
            fix_headers_for_updated_response(response)
            return response
        elif action == "DescribeTimeToLive":
            response = Response()
            response.status_code = 200
            if data["TableName"] in self._table_ttl_map:
                if self._table_ttl_map[data["TableName"]]["Status"]:
                    ttl_status = "ENABLED"
                else:
                    ttl_status = "DISABLED"
                response._content = json.dumps(
                    {
                        "TimeToLiveDescription": {
                            "AttributeName": self._table_ttl_map[data["TableName"]][
                                "AttributeName"
                            ],
                            "TimeToLiveStatus": ttl_status,
                        }
                    }
                )
            else: