No device attached to adb server even if Anbox is running

[Gary.Wang]

To reproduce this issue:
 1. Launch a Anbox instance with
    $ amc launch -r
 2. Install adb deb package from the achieve
    $ amc exec "$instance_id" -- sh -c "apt update && apt install adb -y"
 3. List the devices and `emulator-5558` device should be online
    $ amc exec "$instance_id" -- sh -c "adb devices"
 4. Kill adb server, then list devices again
    $ amc exec "$instance_id" -- sh -c "adb kill-server && adb devices"

Actual result:
    The list of devices attached is empty

Expected result:
    emulator device should be online