Make sure desktop task view is only used in proto 2

When swiping up to recents and creating the current tasks TaskView, we
were checking for proto 1 or proto 2 to be enabled. And if they were, we
were creating the DesktopTaskView object. The DesktopTaskView should
only be enabled in proto 2.
Updated the feature flag check.

Bug: 273950066
Test: enable proto 1 and gesture nav, have a desktop app open, swipe up
  to recents, no desktop tile
Test: enable proto 2 and gesture nav, have a desktop app open, swipe up
  to recents, see the desktop tile
Change-Id: I73a47347d60e0f57ad6cf6e363a6fe83ac8cc509

quickstep/src/com/android/quickstep/views/RecentsView.java

@@ -2614,7 +2614,7 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
     }
 
     private boolean hasDesktopTask(Task[] runningTasks) {
-        if (!DESKTOP_MODE_SUPPORTED) {
+        if (!DesktopTaskView.DESKTOP_IS_PROTO2_ENABLED) {
             return false;
         }
         for (Task task : runningTasks) {