Add new build info metrics that contains more info (#13876)

* Add new build info metrics that contains more info

The goal was to add more information about Grafana. But rather than
just adding those to the current metrics I created a new metric
since its a common pattern in the prometheus community to expose that
info in a metric named `*_build_info`.

We keep the old metric to avoid introducing any breaking changes but
we should be able to remove it the next breaking change

pkg/cmd/grafana-server/main.go

@@ -80,7 +80,7 @@ func main() {
 	setting.BuildBranch = buildBranch
 	setting.IsEnterprise = extensions.IsEnterprise
 
-	metrics.M_Grafana_Version.WithLabelValues(version).Set(1)
+	metrics.SetBuildInformation(version, commit, buildBranch)
 
 	server := NewGrafanaServer()