### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

PutMetricData with arrays of values does not work properly. Zero values seem to be published. PutMetricData with a single value works as expected. This happens to both CLI and SDK.

### Expected Behavior

PutMetricData with arrays of values should work as publishing a single value.

### How are you starting LocalStack?

With a `docker run` command

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    docker run localstack/localstack:1.2.0

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)
```
awslocal cloudwatch put-metric-data --namespace test --metric-data MetricName=TestCounter,Values=10,1,Counts=1,1
awslocal cloudwatch get-metric-statistics --namespace test --metric-name TestCounter --statistics Maximum --period 60 --start-time 2022-11-9T00:00:00Z --end-time 2022-11-11T00:00:00Z
{
    "Label": "TestCounter",
    "Datapoints": [
        {
            "Timestamp": "2022-11-09T23:25:10+00:00",
            "Maximum": 0.0,
            "ExtendedStatistics": {}
        },
        {
            "Timestamp": "2022-11-09T23:27:10+00:00",
            "Maximum": 0.0,
            "ExtendedStatistics": {}
        }
    ]
}
```



### Environment

```markdown
- OS: Mac Monterey
- LocalStack: 1.2.0
```


### Anything else?

_No response_
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):
        self.alarm_scheduler.shutdown_scheduler()
    def delete_alarms(self, context: RequestContext, alarm_names: AlarmNames) -> None:
        moto.call_moto(context)
        for alarm_name in alarm_names:
            arn = arns.cloudwatch_alarm_arn(alarm_name)
            self.alarm_scheduler.delete_scheduler_for_alarm(arn)
    def get_raw_metrics(self, request: Request):