Fixes GestureLauncherService triggering on long press.

This change modifies the logic in GestureLauncherService which handles
key down events on the power key so that it ignores events associated
with a long press.  This prevents the camera from being launched when
a long press occurs within the double-tap threshold, such as when it's
generated by ADB.

Test: atest GestureLauncherServiceTest
Change-Id: I174c338ec3f46cf338ad417bfc551729e4ecd516
Fixes: 116697919