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# Type of request: This is a ...

[x ] bug report
[ ] feature request

# Detailed description

Not able to use the edge service to write metric data to cloudwatch via the javascript aws-sdk.

However, It **DOES** work when using the deprecated cloudwatch port.

## Expected behavior

Metric data to be visible when calling `awslocal cloudwatch list-metrics`

## Actual behavior

404 from edge service. No metric data is persisted, localstack instance logs the following info:

```
INFO:localstack.services.edge: Unable to determine forwarding port for API "monitoring" - please make sure this API is enabled via the SERVICES configuration
```

# Steps to reproduce

Run JS code in "Client code" section.
See 404 Error

## Command used to start LocalStack

`TMPDIR=/tmp/localstack docker-compose up`

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)

```js
const AWS = require('aws-sdk')
const cw = new AWS.CloudWatch({
  endpoint: 'http://localhost:4566',
})

const data = {
  Namespace: 'ns',
  MetricData: [
    {
      MetricName: 'metric-name',
      Timestamp: new Date(),
      Value: 12345,
      Unit: 'Milliseconds',
      Dimensions: [
        { Name: 'Environment', Value: 'local' },
      ]
    }
  ]
}

cw.putMetricData(data, (err, data) => {
  if (err) {
      console.log('Error', err)
  } else {
      console.log('Success', JSON.stringify(data))
  }
})
```

""" Create the final response for the given invocation result """
        if isinstance(result, Response):
            return result
        details = {
            'StatusCode': status_code,
            'Payload': result,
            'Headers': headers
        }
        if isinstance(result, dict):
            for key in ('StatusCode', 'Payload', 'FunctionError'):
                if result.get(key):
                    details[key] = result[key]
        
        was_json = False
        payload = details['Payload']
        if payload and isinstance(payload, POSSIBLE_JSON_TYPES) and payload[0] in JSON_START_CHARS:
            try:
                details['Payload'] = json.loads(details['Payload'])
                was_json = True
            except Exception:
                pass
        
        if details.get('FunctionError'):
            details['Headers']['X-Amz-Function-Error'] = str(details['FunctionError'])
        
        response_obj = details['Payload']
        if was_json or isinstance(response_obj, JSON_START_TYPES):