### 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_
namespaces = [
            "ns1-%s" % short_uid(),
            "ns2-%s" % short_uid(),
            "ns3-%s" % short_uid(),
        ]
        num_dimensions = 2
        for ns in namespaces:
            for i in range(3):
                rs = cloudwatch_client.put_metric_data(
                    Namespace=ns,
                    MetricData=[
                        {
                            "MetricName": "someMetric",
                            "Value": 123,
                            "Dimensions": [
                                {
                                    "Name": "foo",
                                    "Value": "bar-%s" % (i % num_dimensions),
                                }
                            ],
                        }
                    ],
                )
                assert 200 == rs["ResponseMetadata"]["HTTPStatusCode"]
        rs = cloudwatch_client.list_metrics()
        metrics = [m for m in rs["Metrics"] if m.get("Namespace") in namespaces]
        assert metrics
        assert len(metrics) == len(namespaces) * num_dimensions
    def test_describe_alarms_converts_date_format_correctly(self, cloudwatch_client):