### 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_
alarm_name = "a-%s" % short_uid()
        cloudwatch_client.put_metric_alarm(
            AlarmName=alarm_name,
            EvaluationPeriods=1,
            ComparisonOperator="GreaterThanThreshold",
        )
        try:
            result = cloudwatch_client.describe_alarms(AlarmNames=[alarm_name])
            alarm = result["MetricAlarms"][0]
            assert isinstance(alarm["AlarmConfigurationUpdatedTimestamp"], datetime)
            assert isinstance(alarm["StateUpdatedTimestamp"], datetime)
        finally:
            cloudwatch_client.delete_alarms(AlarmNames=[alarm_name])
    def test_put_composite_alarm_describe_alarms_converts_date_format_correctly(
        self, cloudwatch_client
    ):
        alarm_name = "a-%s" % short_uid()
        alarm_rule = 'ALARM("my_other_alarm")'
        cloudwatch_client.put_composite_alarm(
            AlarmName=alarm_name,
            AlarmRule=alarm_rule,
        )
        try:
            result = cloudwatch_client.describe_alarms(AlarmNames=[alarm_name])
            alarm = result["CompositeAlarms"][0]
            assert alarm["AlarmName"] == alarm_name
            assert alarm["AlarmRule"] == alarm_rule
        finally:
            cloudwatch_client.delete_alarms(AlarmNames=[alarm_name])
    def test_store_tags(self, cloudwatch_client):