Custom metrics should differentiate when idling content-repo or jenkins

[chmouel]

This code for custom metrics here :

https://github.com/fabric8-services/fabric8-jenkins-idler/blob/master/internal/api/api.go#L92-L100

Just record Idle, it should probably tell which service it is (content-repo or jenkins)

[lordofthejars]

Notice that https://github.com/fabric8-services/fabric8-jenkins-idler/blob/master/internal/api/api.go#L94 I am sending the service value as well, which contains these strings. https://github.com/fabric8-services/fabric8-jenkins-idler/blob/master/internal/api/api.go#L28