Datasource metrics are not always exposed by the metrics subsystem

The metrics subsystem install a service at RUNTIME to register any metrics on the resources registered in WildFly management tree.

However, the metrics for datasources are provided by the statistics=jdbc and statistics=pool children of the datasource resource which are installed at RUNTIME.

Since there is no dependency between the metrics service and the service that installs the datasource statistics, it is possible that the metrics services is started before and while traverse the WildFly management tree before the statistics resources are added to it.

This issue is intermittent and depend on the sequence of execution of unrelated services.

To circumvent this issue, the metrics subsystem could install its service at VERIFY stage (instead of RUNTIME) and will then have the guarantee that any resources created at RUNTIME is present in WildFly management tree.