Prometheus: Move converter in prometheus package (#82269)

* use jsoniter from sdk

* move converter into the prometheus

* remove jsonitere

* unit test

* remove redundant ownership

.github/CODEOWNERS

@@ -269,7 +269,6 @@
 /pkg/services/searchV2/ @grafana/grafana-app-platform-squad
 /pkg/services/store/ @grafana/grafana-app-platform-squad
 /pkg/infra/filestorage/ @grafana/grafana-app-platform-squad
-/pkg/util/converter/ @grafana/grafana-app-platform-squad
 /pkg/modules/ @grafana/grafana-app-platform-squad
 /pkg/kindsysreport/ @grafana/grafana-app-platform-squad
 /pkg/services/grpcserver/ @grafana/grafana-app-platform-squad