Consider allowing adb backups

[jody-frankowski]

I am not sure why it would be disabled, but right now adb backups seem to be blocked.

[brarcher]

Honestly, I do not know how the backup mechanism works and have never used it myself. Instead, I use the export mechanism in the app to output backup. If someone were interested in getting the adb backup mechanism to work and add some tests, I'd gladly review the pull request.