Acquire a wakelock before sending KEYCODE_SLEEP

To prevent device testing via ADB over ethernet entering standby mode,
acquire a wake lock before sending KEYCODE_SLEEP to device.

We might lose connection when device entering standby mode, end up fail the test.

Test: atest com.android.cts.net.HostsideRestrictBackgroundNetworkTests#testDozeModeNonMetered_whitelisted

Bug: 233154541

Change-Id: I09e0af35d32a8001913d3414c0c41ffbb10ace3d
Merged-In: Icb28d2db6f25bd12ba00f56e5d6e56fa108bdcbd
2 files changed