Replace emulator_system.mk with multidisplay.mk am: 86e50cfebf am: 69e4a05068 am: f2bdcb4e46

Original change: https://android-review.googlesource.com/c/device/generic/car/+/2813935

Change-Id: I0f7fca46e223e1673ac23625dcf3eef87520132e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>