### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

I'm using [Localstack with the Rust SDK](https://docs.aws.amazon.com/sdk-for-rust/latest/dg/localstack.html), and it is reporting an error parsing the `RunInstancesResponse` type:

```
Error: Error parsing XML: expected (boolean: `com.amazonaws.ec2#Boolean`)

Caused by:
    0: Error parsing XML: expected (boolean: `com.amazonaws.ec2#Boolean`)
    1: Error parsing XML: expected (boolean: `com.amazonaws.ec2#Boolean`)
```

The response contains this:

```
<ebsOptimized>False</ebsOptimized>
```

which does not conform to the API reference's description of [AttributeBooleanValue](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_AttributeBooleanValue.html), which says that the valid values are `true` or `false`.

### Expected Behavior

The API should return boolean values in lowercase as specified by the Amazon API Reference.

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

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

```yaml
version: "3.8"

services:
  localstack:
    container_name: "${LOCALSTACK_DOCKER_NAME-localstack_main}"
    image: localstack/localstack
    network_mode: bridge
    ports:
      - "127.0.0.1:4510-4559:4510-4559"  # external service port range
      - "127.0.0.1:4566:4566"            # LocalStack Edge Proxy
    environment:
      - DEBUG=${DEBUG-}
      - DATA_DIR=${DATA_DIR-}
      - LAMBDA_EXECUTOR=${LAMBDA_EXECUTOR-}
      - DOCKER_HOST=unix:///var/run/docker.sock
    volumes:
      - "${LOCALSTACK_VOLUME_DIR:-./volume}:/var/lib/localstack"
      - "${DOCKER_SOCK:-/var/run/docker.sock}:/var/run/docker.sock"
```

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

```rust
let ec2: aws_sdk_ec2::Client = ...;
let resp = ec2
    .run_instances()
    .image_id(image_id)
    .max_count(1)
    .min_count(1)
    .key_name(key_name)
    .security_group_ids(gid)
    .subnet_id(sid)
    .send()
    .await?;
```


### Environment

```markdown
- OS: Ubuntu 18.04 LTS
- LocalStack:

localstack_main | LocalStack version: 1.0.2.dev
localstack_main | LocalStack Docker container id: 73a491727a3c
localstack_main | LocalStack build date: 2022-07-20
localstack_main | LocalStack build git hash: e105e488
```
```


### Anything else?

_No response_
message: str,
    code: Optional[int] = 500,
    code_string: Optional[str] = "InternalFailure",
    service: Optional[str] = None,
    xmlns: Optional[str] = None,
):
    response = requests_error_response_xml(
        message, code=code, code_string=code_string, service=service, xmlns=xmlns
    )
    return requests_to_flask_response(response)
def requests_error_response(
    req_headers: Dict,
    message: Union[str, bytes],
    code: int = 500,
    error_type: str = "InternalFailure",
    service: str = None,
    xmlns: str = None,
):
    is_json = is_json_request(req_headers)
    if is_json:
        return requests_error_response_json(message=message, code=code, error_type=error_type)
    return requests_error_response_xml(
        message, code=code, code_string=error_type, service=service, xmlns=xmlns
    )
def is_json_request(req_headers: Dict) -> bool: