### 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
from localstack.utils.server import http2_server
from localstack.utils.serving import Server
from localstack.utils.strings import to_bytes, to_str
from localstack.utils.threads import start_thread
from localstack.utils.urls import path_from_url
LOG = logging.getLogger(__name__)
SERVER_CERT_PEM_FILE = "server.test.pem"
CORS_ALLOWED_HEADERS = [
    "authorization",
    "cache-control",
    "content-length",
    "content-md5",
    "content-type",
    "etag",
    "location",
    "x-amz-acl",
    "x-amz-content-sha256",
    "x-amz-date",
    "x-amz-request-id",
    "x-amz-security-token",
    "x-amz-tagging",
    "x-amz-target",
    "x-amz-user-agent",
    "x-amz-version-id",
    "x-amzn-requestid",
    "x-localstack-target",
    
    "amz-sdk-invocation-id",
    "amz-sdk-request",
]