Replace uses of ServiceName virtualHostName with use of the capability in RTS subsystem

This issue is created based on the discussion https://github.com/wildfly/wildfly/pull/16710/files#r1162739833

Replace uses of ServiceName virtualHostName with use of the capability in RTS subsystem In RTSSubsystemAdd.java

Supplier<Host> hostSupplier = builder.requires(UndertowService.virtualHostName(serverName, hostName));