[WFLY-1888] Remove unsupported mod_cluster metrics notices
Revert "WFLY-1888 change mod_cluster default metric to cpu (which is a pretty good default metric anyway) from currently unsupported busyness"
This reverts commit 3d7e76ca8fe0427b9fb374f27291cbd3d22cdbe2.
[WFLY-1888] Implement mod_cluster request count metrics via custom HttpHandler
[WFLY-1888] Implement mod_cluster traffic/bytes sent/received metrics
[WFLY-1888] backport LongAdder/Striped64 instead of introducing an inconvenient dependency
[WFLY-1888] fix checkstyle errors and module deps in JDK8 imported classes