Merge "Revert "Revert "Adding unit tests for ConcurrentSkipListMap""" am: 70ab131d26 am: af54f29cd9 am: 4b326b1096

Original change: https://android-review.googlesource.com/c/platform/libcore/+/1697669

Change-Id: I85661635dcdf7b5c24ef92cb9e94253706e3142f