Remove unneeded art::Unit member functions am: 6ff274b4a0 am: f8a005ef84 am: 5e77a4ec74

Original change: https://android-review.googlesource.com/c/platform/art/+/2200113

Change-Id: Ibd901768b2e62a4e1153f542b7c1c340412a533d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>