Merge "Add RandomGenerator.SplittableGenerator test coverage." into main am: df68469ab0 am: 6f14803652

Original change: https://android-review.googlesource.com/c/platform/libcore/+/2977891

Change-Id: I2d07e09beca96b23bc4b1cb34ee60dfbe57cdab6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>