fix(cloudwatch): use correct metric statistic for IncomingLogEvents (#589)

Fixes #588

---

_By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache-2.0 license_

Co-authored-by: Chesley Pappas <[email protected]>

Author: chesleypappas

lib/monitoring/aws-cloudwatch/CloudWatchLogsMetricFactory.ts

@@ -34,7 +34,7 @@ export class CloudWatchLogsMetricFactory extends BaseMetricFactory<CloudWatchLog
   metricIncomingLogEvents() {
     return this.metricFactory.createMetric(
       "IncomingLogEvents",
-      MetricStatistic.N,
+      MetricStatistic.SUM,
       "Logs",
       this.dimensionsMap,
       undefined,