Use gitlab_fingerprint instead of payload_key

`CreateEventsService` now uses `Alerting::Alert#gitlab_fingerprint`
instead of `.payload_keys` from `PrometheusAlertEvent` and
`SelfManagedPrometheusAlertEvent` models.`

app/services/projects/prometheus/alerts/create_events_service.rb

@@ -40,17 +40,13 @@ module Projects
 
         def create_managed_prometheus_alert_event(parsed_alert)
           alert = find_alert(parsed_alert.metric_id)
-          payload_key = PrometheusAlertEvent.payload_key_for(parsed_alert.metric_id, parsed_alert.starts_at_raw)
-
-          event = PrometheusAlertEvent.find_or_initialize_by_payload_key(parsed_alert.project, alert, payload_key)
+          event = PrometheusAlertEvent.find_or_initialize_by_payload_key(parsed_alert.project, alert, parsed_alert.gitlab_fingerprint)
 
           set_status(parsed_alert, event)
         end
 
         def create_self_managed_prometheus_alert_event(parsed_alert)
-          payload_key = SelfManagedPrometheusAlertEvent.payload_key_for(parsed_alert.starts_at_raw, parsed_alert.title, parsed_alert.full_query)
-
-          event = SelfManagedPrometheusAlertEvent.find_or_initialize_by_payload_key(parsed_alert.project, payload_key) do |event|
+          event = SelfManagedPrometheusAlertEvent.find_or_initialize_by_payload_key(parsed_alert.project, parsed_alert.gitlab_fingerprint) do |event|
             event.environment      = parsed_alert.environment
             event.title            = parsed_alert.title
             event.query_expression = parsed_alert.full_query

spec/services/projects/prometheus/alerts/create_events_service_spec.rb

@@ -89,9 +89,9 @@ describe Projects::Prometheus::Alerts::CreateEventsService do
     context 'with a resolved payload' do
       let(:started_at) { truncate_to_second(Time.current) }
       let(:ended_at) { started_at + 1 }
-      let(:payload_key) { PrometheusAlertEvent.payload_key_for(alert.prometheus_metric_id, utc_rfc3339(started_at)) }
       let(:resolved_event) { alert_payload(status: 'resolved', started_at: started_at, ended_at: ended_at) }
       let(:alerts_payload) { { 'alerts' => [resolved_event] } }
+      let(:payload_key) { Gitlab::Alerting::Alert.new(project: project, payload: resolved_event).gitlab_fingerprint }
 
       context 'with a matching firing event' do
         before do