Log unset minimize and unminimize reasons in DesktopModeEventLogger

When updating the DesktopModeSessionTaskUpdate atom we need to update
the corresponding FrameworkStatsLog.write() logging calls. In this CL
we update the calls to add empty minimize and unminimize reasons.

Bug: 358002042
Test: manual
Flag: com.android.window.flags.enable_desktop_windowing_task_limit
Change-Id: I487dabe109ee51a137139278174a446eeab9d4b2