### 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.
(a language to define services in a - somewhat - protocol-agnostic
way). The "peculiarities" in this serializer code usually correspond
to certain so-called "traits" in Smithy.
The result of the serialization methods is the HTTP response which can
be sent back to the calling client.
**Experimental:** The serializers in this module are still experimental.
When implementing services with these serializers, some edge cases might
not work out-of-the-box.
"""
import abc
import base64
import functools
import json
import logging
from abc import ABC
from binascii import crc32
from datetime import datetime
from email.utils import formatdate
from struct import pack
from typing import Any, Iterable, Iterator, Optional, Tuple, Union
from xml.etree import ElementTree as ETree
from boto.utils import ISO8601
from botocore.model import ListShape, MapShape, OperationModel, ServiceModel, Shape, StructureShape
from botocore.serialize import ISO8601_MICRO
from botocore.utils import calculate_md5, is_json_value_header, parse_to_aware_datetime
from moto.core.utils import gen_amzn_requestid_long
from localstack.aws.api import HttpResponse, ServiceException
from localstack.utils.common import to_bytes, to_str
LOG = logging.getLogger(__name__)
class ResponseSerializerError(Exception):