Skip updating device in build only mode and add metric

Previously, device update method would be executed even atest is running in build only mode. Build only mode is supposed to not require a device, updating device at this mode may cause error.
Also adds a metric to record the device update time.

Fix: 367419073
Test: atest_unittests
Change-Id: I94ed4c74d4bf34d14d7323e12ec01986e0d83fdd