### 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_
AlarmName=alarm_name, StateReason=state_reason, StateValue=state_value
            )
            retry(
                check_message,
                retries=PUBLICATION_RETRIES,
                sleep_before=1,
                sqs_client=sqs_client,
                expected_queue_url=queue_url_ok,
                expected_topic_arn=topic_arn_ok,
                expected_new=state_value,
                expected_reason=state_reason,
                alarm_name=alarm_name,
                alarm_description=alarm_description,
                expected_trigger=expected_trigger,
            )
        finally:
            
            sns_client.unsubscribe(SubscriptionArn=subscription_alarm["SubscriptionArn"])
            sns_client.unsubscribe(SubscriptionArn=subscription_ok["SubscriptionArn"])
            cloudwatch_client.delete_alarms(AlarmNames=[alarm_name])
    @pytest.mark.aws_validated
    @pytest.mark.skip_snapshot_verify(
        paths=[
            "$..evaluatedDatapoints",
            "$..startDate",  
            "$..alarm-triggered-describe.MetricAlarms[0].StateReason",  
            "$..alarm-triggered-sqs-msg.NewStateReason",
        ]
    )
    def test_put_metric_alarm(