Merge "Revert "Migrate the blkio controller to the v2 cgroup hierarchy"" am: ddfa08b98b

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2378329

Change-Id: I6921de70695044f30a18f2bd035545b8eb15ef13
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>