Refactor Memory Balloon control routines am: 96d3f942d4

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Virtualization/+/3539280

Change-Id: I8bae48892b71aa2d6c25860b66e98589d79d0b94
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>