### 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, sns_client, cloudwatch_client, sqs_client, sns_create_topic, sqs_create_queue
    ):
        
        sns_topic_alarm = sns_create_topic()
        topic_arn_alarm = sns_topic_alarm["TopicArn"]
        sns_topic_ok = sns_create_topic()
        topic_arn_ok = sns_topic_ok["TopicArn"]
        
        uid = short_uid()
        queue_url_alarm = sqs_create_queue(QueueName=f"AlarmQueue-{uid}")
        queue_url_ok = sqs_create_queue(QueueName=f"OKQueue-{uid}")
        arn_queue_alarm = sqs_client.get_queue_attributes(
            QueueUrl=queue_url_alarm, AttributeNames=["QueueArn"]
        )["Attributes"]["QueueArn"]
        arn_queue_ok = sqs_client.get_queue_attributes(
            QueueUrl=queue_url_ok, AttributeNames=["QueueArn"]
        )["Attributes"]["QueueArn"]
        sqs_client.set_queue_attributes(
            QueueUrl=queue_url_alarm,
            Attributes={"Policy": get_sqs_policy(arn_queue_alarm, topic_arn_alarm)},
        )
        sqs_client.set_queue_attributes(
            QueueUrl=queue_url_ok, Attributes={"Policy": get_sqs_policy(arn_queue_ok, topic_arn_ok)}
        )
        alarm_name = "test-alarm"
        alarm_description = "Test Alarm when CPU exceeds 50 percent"
        expected_trigger = {
            "MetricName": "CPUUtilization-3",
            "Namespace": "AWS/EC2",