Do not allow GlanceableHub touch monitor to outlive view.

This changelist ensures that the touch monitor associated with the
glanceable hub is torn down whenever the backing view is disposed. This
ensures the backing input session never participates beyond the view
lifespan.

Test: atest GlanceableHubContainerControllerTest#disposeView_destroysTouchMonitor
Flag: EXEMPT bugfix
Fixes: 367549056
Change-Id: Iebb58ac941bee3ee9ed94b55d752f6e9a90780bd