Fix lunch choices for git_main am: cff9d02a9c

Original change: https://android-review.googlesource.com/c/device/generic/art/+/2811333

Change-Id: I81fc81a812d227f5e026030b7d87365bfbbe0fce
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>