Fix not releasing touching state of the handle on divider bar

After ag/14340443, the touching state of divider handle won't be reset
after tapping on divider bar. This makes sure to reset touching state
whenever received cancel/up touch event.

Bug: 186626153
Test: atest WMShellUnitTests
Test: check the touching of the handle on divider bar will be reset
after single tapping on divider bar.

Change-Id: I8645d17cda8833aa75b108f863e48655a7c87feb