### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When a scheduled rules runs, an empty event is generated and sent to targets.

### Expected Behavior

An event like this sample should be sent.
```json
{
  "version": "0",
  "id": "89d1a02d-5ec7-412e-82f5-13505f849b41",
  "detail-type": "Scheduled Event",
  "source": "aws.events",
  "account": "123456789012",
  "time": "2016-12-30T18:44:49Z",
  "region": "us-east-1",
  "resources": ["arn:aws:events:us-east-1:123456789012:rule/SampleRule"],
  "detail": {}
}
```

### 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`)

    docker-compose up

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

    awslocal events put-rule --name scheduled_rule --schedule-expression "rate(1 minutes)"
    awslocal events put-targets --rule scheduled_rule --targets "Id"="1","Arn"="arn:aws:logs:us-east-1:000000000000:log-group:/aws/events/echo"
    awslocal--endpoint-url=http://localhost:4566 logs tail "/aws/events/echo"

### Environment

```markdown
- OS: macOS Monterey
- LocalStack: 0.13.3
```


### Anything else?
I think [this](https://github.com/localstack/localstack/blob/1567f25a8f672f4dec23cb7cb1aadb5a744366f8/localstack/services/events/events_listener.py#L92) means an non-empty event is sent only when an input is `Constant (JSON text)`.
![image](https://user-images.githubusercontent.com/4127030/151643813-a4d1e113-dba3-41ad-8400-da57e4f674a1.png)

r"^{}".format(element_value.get(nested_key)), event_value
                    ):
                        return True
    return False
def handle_prefix_filtering(event_pattern, value):
    for element in event_pattern:
        if isinstance(element, (int, str)):
            if str(element) == str(value):
                return True
            if element in value:
                return True
        elif isinstance(element, dict) and "prefix" in element:
            if value.startswith(element.get("prefix")):
                return True
        elif isinstance(element, dict) and "anything-but" in element:
            if element.get("anything-but") != value:
                return True
        elif "numeric" in element:
            return handle_numeric_conditions(element.get("numeric"), value)
        elif isinstance(element, list):
            if value in list:
                return True
    return False
def identify_content_base_parameter_in_pattern(parameters) -> bool:
    return any(
        list(param.keys())[0] in CONTENT_BASE_FILTER_KEYWORDS
        for param in parameters
        if isinstance(param, dict)
    )
def get_two_lists_intersection(lst1: List, lst2: List) -> List: