Add --nowait option to disable waiting after reboots and restarts.

Removes the part where we clear the system property (for restarts) and
the wait-for-device with timeout.

Takes about to 10 secs run now.

Test: adevice --nowait update
Test: adevice update
Test: atest
Bug: 302550045
Change-Id: I3d2c291a2f117419d0f252c9f1aebc95bf8c21c9
6 files changed