Wildfly-Unmanaged: change @beforeclass to @beforesuite as soon as JUnit gets update to version 5

As soon as Narayana moves to JUnit 5, there will be the possibility to use @BeforeSuite. This tag is particularly worth in situation where some operations need to be run before testing suite. This could be the case of tests where an instance of Wildfly needs to be kept alive for the entire length of the test (e.g. in wildfly-unamanged, the lra-participant Wildfly container could be started with @BeforeSuite)