Qemu: Keep ssh connection to VM open. am: 902ee14fd6

Original change: https://android-review.googlesource.com/c/platform/art/+/2984873

Change-Id: Idc91ef591398d08eb57f7dad1498f4bb29c5eb15
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>