### 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_
sqs_client,
    expected_queue_url,
    expected_topic_arn,
    expected_new,
    expected_reason,
    alarm_name,
    alarm_description,
    expected_trigger,
):
    receive_result = sqs_client.receive_message(QueueUrl=expected_queue_url)
    message = None
    for msg in receive_result["Messages"]:
        body = json.loads(msg["Body"])
        if body["TopicArn"] == expected_topic_arn:
            message = json.loads(body["Message"])
            receipt_handle = msg["ReceiptHandle"]
            sqs_client.delete_message(QueueUrl=expected_queue_url, ReceiptHandle=receipt_handle)
            break
    assert message["NewStateValue"] == expected_new
    assert message["NewStateReason"] == expected_reason
    assert message["AlarmName"] == alarm_name
    assert message["AlarmDescription"] == alarm_description
    assert message["Trigger"] == expected_trigger
    return message
def get_sqs_policy(sqs_queue_arn, sns_topic_arn):