[Alerting][Event log] Persisting duration information for active alerts in event log (#101387)

* WIP

* Storing start, duration and end in alert state

* Writing to event log

* Updating unit tests

* Adding unit tests

* Fixing uuid in tests

* Updating functional test

* Adding functional test

* Removing console logs

* Fixing unit tests

* PR fixes

* Removing uuid from alert information

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

Author: ymao1