Hook up Go recents view API to recents activity

Hook up onBeginTransitionToOverview for fallback recents as well by
hooking it up to activity start.

Bug: 114136250
Test: Go to recents for fallback recents
Change-Id: I5445bce13ecf7c0dbc2f2b3ff0d8a0aee1449ae1

go/quickstep/src/com/android/quickstep/RecentsActivity.java

@@ -67,9 +67,7 @@ public final class RecentsActivity extends BaseRecentsActivity {
 
     @Override
     protected void onStart() {
-        // Set the alpha to 1 before calling super, as it may get set back to 0 due to
-        // onActivityStart callback.
-        mIconRecentsView.setAlpha(0);
+        mIconRecentsView.onBeginTransitionToOverview();
         super.onStart();
     }
 }

go/quickstep/src/com/android/quickstep/views/IconRecentsView.java

@@ -144,8 +144,6 @@ public final class IconRecentsView extends FrameLayout {
      * Logic for when we know we are going to overview/recents and will be putting up the recents
      * view. This should be used to prepare recents (e.g. load any task data, etc.) before it
      * becomes visible.
-     *
-     * TODO: Hook this up for fallback recents activity as well
      */
     public void onBeginTransitionToOverview() {
         // Load any task changes