Include triggering metrics to pagerduty alerts
Include triggering metrics to pagerduty alerts

Assist the person receiving the alert in identifying the cause

Based on the slack notifier fields this will include upto 4 triggering
metrics in the custom details section in the pagerduty incident

Fixes #8479

grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana