Replace emulator_system.mk with multidisplay.mk am: 86e50cfebf

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

Change-Id: Icce382b5dba16e249d4eb30121aea10999ee29fb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>