Remove premature bubble collapse from NotificationClicker.

NotificationClicker previously collapsed an expanded bubble
unconditionally when a notification was clicked, unless the bubble
conversation icon on the notification was clicked. This behavior was
problematic, especially with the introduction of app bubbles, because
NotificationClicker lacks the context to determine if the click would
reuse an existing, expanded bubble's task.

This change removes the explicit bubble collapse call from
NotificationClicker. In subsequent changes, BubblesTransitionObserver
will handle the decision to collapse or retain an expanded bubble when
an activity transition occurs. This ensures proper behavior for both
chat and app bubbles.

Bug: 390047887
Bug: 407935283
Flag: EXEMPT bug fix
Test: Manual launch BubbleChat app with bubble
Change-Id: I730be20fc9905a8fb9d6b254413267daa098e09b