### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When calling 

`cloudWatchClient.EnableAlarmActions(&cloudwatch.EnableAlarmActionsInput{AlarmNames: alarmNames})`

with golang I receive a SerializationError with bytes in the error message saying: 

`<!DOCTYPE HTM |UBLIC "-//W3C//DTD HTML 3.2 Final//EN">.<title>500 Internal Server Error</title>.<h1>Internal Server Error</h1>.<p>The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.`

I believe this is a bug, since other cloudwatch operations like "DescribeAlarms" work flawlessly with the same client.

### Expected Behavior

I expected the call to go through without any errors

### How are you starting LocalStack?

With a `docker run` command

### Steps To Reproduce

Start localstack, create alarms and call cloudwatch "EnableAlarmActions"

### Environment

_No response_

### Anything else?

_No response_
def __init__(self, message: str):
        super().__init__("ValidationError", message, 400, True)
class CloudwatchProvider(CloudwatchApi, ServiceLifecycleHook):
    """
    Cloudwatch provider.
    LIMITATIONS:
        - no alarm rule evaluation
    """
    def __init__(self):
        self.tags = TaggingService()
        self.alarm_scheduler = None
    def on_after_init(self):
        ROUTER.add(PATH_GET_RAW_METRICS, self.get_raw_metrics)
        self.alarm_scheduler = AlarmScheduler()
    def on_before_start(self):
        
        def restart_alarms(*args):
            poll_condition(lambda: SERVICE_PLUGINS.is_running("cloudwatch"))
            self.alarm_scheduler.restart_existing_alarms()
        start_worker_thread(restart_alarms)
    def on_before_stop(self):