Merge "Add SplittableRandom test coverage." into main am: 15ad3bc9fa

Original change: https://android-review.googlesource.com/c/platform/libcore/+/2977254

Change-Id: Ic72e491a95293fe654b7f26639c3b90e6be699f3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>