### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

In AWS, DescribeSubnet Response returns:
```
<?xml version="1.0" encoding="UTF-8"?>\n
    <Response>
        <Errors>
            <Error>
                <Code>InvalidSubnetID.NotFound</Code>
                <Message>The subnet ID \'test\' does not exist</Message>
            </Error>
        </Errors>
    <RequestID>f6d041c1-1c96-4720-af30-77745504e2ba</RequestID>
</Response>
```

whereas localstack returns:
```
<?xml version=\'1.0\' encoding=\'utf-8\'?>\n<Errors xmlns="http://ec2.amazonaws.com/doc/2016-11-15">
    <Error>
        <Code>InvalidSubnetID.NotFound</Code>
        <Message>aaThe subnet ID \'vpc-test\' does not exist</Message>
    </Error>
    <RequestID>EADJHWMM796CI5FT10XGFMGOXIPCBAHBWINMV0HR6SKBRODGCU5J</RequestID>
</Errors>

```

### Expected Behavior

It should return correct response structure. It causes terraform to complain.

### How are you starting LocalStack?

Custom (please describe below)

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    make start

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

     awslocal ec2 describe-subnets --subnet-ids vpc-test --debug


### Environment

```markdown
- OS: M1 MacOS
- LocalStack: 1.0.2.dev
```


### Anything else?

Probably `call_moto` function in `localstack/services/moto.py` is changing the error code structure.
return str(error) if error is not None and str(error) != "None" else None
class BaseXMLResponseSerializer(ResponseSerializer):
    """
    The BaseXMLResponseSerializer performs the basic logic for the XML response serialization.
    It is slightly adapted by the QueryResponseSerializer.
    While the botocore's RestXMLSerializer is quite similar, there are some subtle differences (since botocore's
    implementation handles the serialization of the requests from the client to the service, not the responses from the
    service to the client).
    **Experimental:** This serializer is still experimental.
    When implementing services with this serializer, some edge cases might not work out-of-the-box.
    """
    def _serialize_error(
        self,
        error: ServiceException,
        response: HttpResponse,
        shape: StructureShape,
        operation_model: OperationModel,
    ) -> None:
        # Check if we need to add a namespace
        attr = (
            {"xmlns": operation_model.metadata.get("xmlNamespace")}
            if "xmlNamespace" in operation_model.metadata
            else {}
        )