The current GPU Ruby Random tester tests only test for WT L2 caches, meaning that some transitions (specific to WB caches) are never tested. To help ensure better coverage, this commit adds a separate test that tests WB GPU L2 caches to the per-checkin and nightly regressions. Change-Id: I539ece3b825b9a38630027d947dc11ebef588752 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/69258 Tested-by: kokoro <noreply+kokoro@google.com> Maintainer: Bobby Bruce <bbruce@ucdavis.edu> Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>