Keycloak metrics

[shaidar]

Description/Context

We currently rely on https://github.com/aerogear/keycloak-metrics-spi to expose Keycloak metrics which we then ship to hosted Grafana through vector. The new release of Keycloak provides guides to two Grafana dashboards and the plugin that we have been relying on does not appear to be that active lately given that the last commit was about 5 months ago.

We should remove the metrics plugin from our pipeline and make the necessary Keycloak changes to expose Keycloak metrics with the built-in feature.

[shaidar]

The keycloak metrics endpoint along with the healthcheck one are both configured and up and running on CI. Turning on events in the UI, doesn't appear to enable user and admin events for the metrics endpoint. Had to pass another startup flag to get the metrics endpoint to show those stats. Setup the Grafana dashboards from the Keycloak repo however i wasn't seeing any metrics flowing through. Verified that the vector client is scraping the new metrics url (port 9000) and verified that the metrics endpoint has data for the stats that the Grafana dashboard is querying for.