Desks: Update repository active desk even if with-task not found

It's possible an ActivateDeskWithTask transition does not contain the
change for the taskId initially requested to enter desktop, such as when
the requested task trampolines into another task. With this change, the
desk activation state is updated regardless. The task update is ok to
skip because DesktopTaskChangeListener handles individual task updates
anyway.

Flag: com.android.window.flags.enable_multiple_desktops_backend
Fix: 419744334
Test: atest DesksTransitionObserverTest
Test: in a desktop-first display, in Home, launch Calendar from taskbar
or all apps - verify desk is activated in repository.

Change-Id: I53ee968993d0fb7d0d05862ababd5b24b6517998