### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

We are using the `Authorization` header for routing purposes

```
 "authorization: AWS4-HMAC-SHA256 <...>"
```

https://github.com/localstack/localstack/issues/5770

### Expected Behavior

Use a custom header to avoid causing confusion with backend integrations

### How are you starting LocalStack?

With a `docker run` command

### Steps To Reproduce

Run a custom HTTP integration without authorisation

### Environment

```markdown
- OS: 
- LocalStack:
```


### Anything else?

No
"""Determine API and backend port based on "Authorization" or "Host" headers."""
    
    result = API_UNKNOWN, 0
    target = headers.get("x-amz-target", "")
    host = headers.get("host", "")
    auth_header = headers.get("authorization", "")
    if not auth_header and not target and "." not in host:
        return result[0], result[1], path, host
    path = path or "/"
    
    try:
        service = extract_service_name_from_auth_header(headers)
        assert service
        result = service, get_service_port_for_account(service, headers)
    except Exception:
        pass
    result_before = result
    
    if host.endswith("cloudfront.net"):
        path = path or "/"
        result = "cloudfront", config.service_port("cloudfront")
    elif target.startswith("AWSCognitoIdentityProviderService") or "cognito-idp." in host:
        result = "cognito-idp", config.service_port("cognito-idp")
    elif target.startswith("AWSCognitoIdentityService") or "cognito-identity." in host:
        result = "cognito-identity", config.service_port("cognito-identity")
    elif result[0] == "s3" and path.startswith(S3CONTROL_COMMON_PATH):
        result = "s3control", config.service_port("s3control")
    elif result[0] == "s3" or uses_host_addressing(headers):
        result = "s3", config.service_port("s3")