Use reorder instead of hidden for bubble task visibility.

This change modifies how bubble tasks are shown and hidden by using
reordering instead of the hidden property. It is part of a larger effort
to support bubble'd app task to fullscreen transitions.

The key change is in TaskViewController#setTaskViewVisible, where the
alwaysOnTop flag is now set/reset, and the task is reordered to the
top/bottom when visibility is true/false. BubbleTaskViewController is
overridden to call the parent method with reorder=true and
toggleHiddenOnReorder=true. This removes the need for a transition
handler to reset the task's hidden flag.

This approach ensures the task remains alwaysOnTop and is reordered to
the top when the bubble expands. When the bubble collapses, the task is
no longer alwaysOnTop and is reordered to the bottom, behind the
fullscreen launcher.

Bug: 388630258
Flag: com.android.wm.shell.enable_create_any_bubble
Flag: com.android.window.flags.exclude_task_from_recents
Test: atest WMShellUnitTests:TaskViewTransitionsTest
Test: atest WMShellRobolectricTests:BubbleControllerTest
Test: atest WMShellMultivalentTestsOnDevice:BubbleControllerTest
Change-Id: Ibdc4630258cbe3edcc37c6d4bd8382f2da0c519e