Upgrade emulator to emu-master-dev build 8457838 am: 7c0db0a484 am: d3507c94ad

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

Change-Id: Ie57c4079ddd270bc8cf791032a2ee0199747e8e7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>