Fix nanocore sum for non default intervals on Kubernetes Overview Dashboard (#19675) (#19979)

* Fix nanocore sum for non default intervals on Kubernetes Overview Dashboard
The Kibana visualization CPU usage by node [Metricbeat Kubernetes] ECS did not account for x-axis scaling.
In case the scaling aligned with the value from metricset.period it was correct.
In every other case, the sum was not correctly calculated as it did not take into account how big the buckets in the visualizations would be.

* Add changelog entry for k8s dashboard node usage

(cherry picked from commit 4dcbde3)

Co-authored-by: Jasper Bernhardt <[email protected]>

Author: ChrsMark

CHANGELOG.asciidoc

@@ -33,6 +33,7 @@ https://github.com/elastic/beats/compare/v7.5.0...v7.5.1[View commits]
 - Fix ListMetrics pagination in aws module. {issue}14926[14926] {pull}14942[14942]
 - Fix CPU count in docker/cpu in cases where no `online_cpus` are reported {pull}15070[15070]
 - Add domain state to kvm module {pull}17673[17673]
+- Fix Kubernetes Overview Dashboard to correctly display non 10s intervals for node usage {pull}19675[19675]
 
 [[release-notes-7.5.0]]
 === Beats version 7.5.0

metricbeat/module/kubernetes/_meta/kibana/7/dashboard/Metricbeat-kubernetes-overview.json

@@ -126,6 +126,28 @@
                                         "field": "kubernetes.container.cpu.usage.nanocores",
                                         "id": "0d5c9221-2bf2-11e7-859b-f78b612cde28",
                                         "type": "sum"
+                                    },
+                                    {
+                                        "id": "8b346300-bf95-11ea-a07c-851701f0d645",
+                                        "type": "avg",
+                                        "field": "metricset.period"
+                                    },
+                                    {
+                                        "id": "25ae6580-bf95-11ea-a07c-851701f0d645",
+                                        "type": "calculation",
+                                        "variables": [
+                                            {
+                                                "id": "39e40aa0-bf95-11ea-a07c-851701f0d645",
+                                                "name": "sum_nanocores",
+                                                "field": "0d5c9221-2bf2-11e7-859b-f78b612cde28"
+                                            },
+                                            {
+                                                "id": "85213600-bf95-11ea-a07c-851701f0d645",
+                                                "name": "avg_period",
+                                                "field": "8b346300-bf95-11ea-a07c-851701f0d645"
+                                            }
+                                        ],
+                                        "script": "params.sum_nanocores / (params._interval / params.avg_period)"
                                     }
                                 ],
                                 "override_index_pattern": 0,