Upgrade emulator to emu-master-dev build 8457838 am: 7c0db0a484 am: d3507c94ad am: 293272bc72 am: 0094ffb51f am: 20c2ff9f5d

Original change: https://android-review.googlesource.com/c/platform/prebuilts/android-emulator/+/2065607

Change-Id: Ic7301f5894d85bb23e139b87eb2ce8a0402348bb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>