Clear keyboardFocusTask after Meta+Tab

- keyboardFocusTask caused AbsSwiepUpHandler to map wrong progress to the swipe up animation
- OverviewCommandHelper set keyboardFocusTask in all commands, but only clear it in HIDE_ALT_TAB causing the wrong state to be stuck
- Also clear keyboardFocusTask in reset() just to make sure

Fix: 407050102
Test: Meta+Tab, launch task, then swipe up
Test: Alt+Tab to switch to Overview
Flag: EXEMPT bug fix
Change-Id: I96ba74e91ce338077af7515b66f249d178897108
2 files changed