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

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

Change-Id: I676446814a19d06dc1713fde64ff1c9fe99cfa36
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>