[Metricbeat] Add aggregation aligner as a config param for stackdrive…

…r metricset in GCP (#17719) (#17979)

* Add metricDescriptor to get sample period and ingest delay time
* add aggregation for ListTimeSeriesRequest
* Add aligner into metric name suffix (eg: .avg, .sum)

(cherry picked from commit 98f02e1)

CHANGELOG.next.asciidoc

@@ -417,6 +417,8 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Refactor windows/perfmon metricset configuration options and event output. {pull}17596[17596]
 - Reference kubernetes manifests mount data directory from the host when running metricbeat as daemonset, so data persist between executions in the same node. {pull}17429[17429]
 - Add more detailed error messages, system tests and small refactoring to the service metricset in windows. {pull}17725[17725]
+- Stack Monitoring modules now auto-configure required metricsets when `xpack.enabled: true` is set. {issue}16471[[16471] {pull}17609[17609]
+- Add aggregation aligner as a config parameter for googlecloud stackdriver metricset. {issue}17141[[17141] {pull}17719[17719]
 - Move the perfmon metricset to GA. {issue}16608[16608] {pull}17879[17879]
 - Stack Monitoring modules now auto-configure required metricsets when `xpack.enabled: true` is set. {issue}16471[[16471] {pull}17609[17609]