AlertManager collect metrics on traffic it receives

[emanlodovice]

Is your feature request related to a problem? Please describe.
Because majority of the traffic the AlertManager receives can be coming from ruler, the request will not be seen in the logs/metrics in the cluster's ingress.

Describe the solution you'd like
To improve observability, I think it would be nice for AM to collect metrics for the traffic it is receiving specially on the create alerts path.

[emanlodovice]

ops we actually have this metric under cortex_request_duration. closing

[qinxx108]

We only have route like "/alertmanagerpb.Alertmanager/HandleRequest", we can't distinguish if the handle request is alerts/silences apis

[stale]

This issue has been automatically marked as stale because it has not had any activity in the past 60 days. It will be closed in 15 days if no further activity occurs. Thank you for your contributions.