### 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_
if existing_item:
                        record["dynamodb"]["OldImage"] = existing_item
        elif action in ("GetItem", "Query"):
            if response.status_code == 200:
                content = json.loads(to_str(response.content))
                
                
                if "ConsumedCapacity" not in content and data.get("ReturnConsumedCapacity") in [
                    "TOTAL",
                    "INDEXES",
                ]:
                    content["ConsumedCapacity"] = {
                        "TableName": table_name,
                        "CapacityUnits": 5,  
                        "ReadCapacityUnits": 2,
                        "WriteCapacityUnits": 3,
                    }
                    response._content = json.dumps(content)
                    fix_headers_for_updated_response(response)
        elif action == "DeleteItem":
            if response.status_code == 200 and event_sources_or_streams_enabled:
                old_item = self._thread_local("existing_item")
                record["eventID"] = short_uid()
                record["eventName"] = "REMOVE"
                record["dynamodb"]["Keys"] = data["Key"]
                record["dynamodb"]["OldImage"] = old_item
                record["dynamodb"]["SizeBytes"] = len(json.dumps(old_item))
                
                stream_spec = dynamodb_get_table_stream_specification(table_name=table_name)
                if stream_spec: