[SysUI][Floaty] Send KeyEvent with FLAG_LONG_PRESS on long power press

Change to ignore power press till the duration of short press will be
taken in follow-up CLs after discussing and finalizing it with the team.

Bug: 399263897
Flag: com.android.systemui.shared.enable_lpp_squeeze_effect
Test: atest PowerKeyGestureTest
Change-Id: I8293d3ecf6057886b24e8dec5970ebbd192c808e