Deprecate the flag -XX:ExplicitGCInvokesConcurrentAndUnloadsClasses

The class -XX:ExplicitGCInvokesConcurrentAndUnloadsClasses is no longer necessary since there already are two flags covering this functionality:
-XX:ExplicitGCInvokesConcurrent
-XX:ClassUnloadingWithConcurrentMark

The above two flags are sufficient to express -XX:+ExplicitGCInvokesConcurrentAndUnloadsClasses, just enable the above two flags :-XX:+ExplicitGCInvokesConcurrent -XX:+ClassUnloadingWithConcurrentMark. Therefore, the flag -XX:ExplicitGCInvokesConcurrentAndUnloadsClasses should be deprecated and removed in a future release, it provides no extra functionality and is cumbersome to validate.