### 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_
for key in ["TableId", "SSEDescription"]:
                    if table_definitions.get(key):
                        content = json.loads(to_str(response.content))
                        content.get("Table", {})[key] = table_definitions[key]
                        update_response_content(response, content)
        elif action == "TagResource":
            table_arn = data["ResourceArn"]
            table_tags = DynamoDBRegion.TABLE_TAGS
            if table_arn not in table_tags:
                table_tags[table_arn] = {}
            table_tags[table_arn].update({tag["Key"]: tag["Value"] for tag in data.get("Tags", [])})
            return
        elif action == "UntagResource":
            table_arn = data["ResourceArn"]
            for tag_key in data.get("TagKeys", []):
                DynamoDBRegion.TABLE_TAGS.get(table_arn, {}).pop(tag_key, None)
            return
        else:
            
            return
        if event_sources_or_streams_enabled and records and "eventName" in records[0]:
            if table_name:
                for record in records:
                    record["eventSourceARN"] = aws_stack.dynamodb_table_arn(table_name)
            EventForwarder.forward_to_targets(records, background=True)
    
    
    
    @classmethod
    def prepare_request_headers(cls, headers):