### 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) -> None:
        """
        Creates a new AlarmScheduler, with a Scheduler, that will be started in a new thread
        """
        super().__init__()
        self.scheduler = Scheduler()
        self.thread = threading.Thread(target=self.scheduler.run)
        self.thread.start()
        self.scheduled_alarms = {}
    def shutdown_scheduler(self) -> None:
        """
        Shutsdown the scheduler, must be called before application stops
        """
        self.scheduler.close()
        self.thread.join(5)
    def schedule_metric_alarm(self, alarm_arn: str) -> None:
        """(Re-)schedules the alarm, if the alarm is re-scheduled, the running alarm scheduler will be cancelled before
        starting a new one"""
        alarm_details = get_metric_alarm_details_for_alarm_arn(alarm_arn)
        self.delete_scheduler_for_alarm(alarm_arn)
        if not self._is_alarm_supported(alarm_details):
            LOG.warning(
                "Given alarm configuration not yet supported, alarm state will not be evaluated."
            )
            return
        period = alarm_details["Period"]
        evaluation_periods = alarm_details["EvaluationPeriods"]
        schedule_period = evaluation_periods * period
        def on_error(e):