Keeping the custom widget placeholder even when the plugin is not corrected

Custom widget plugin can take some time to load, which causes already added
custom widgets to get removed during reboot. Instead keeping the placeHolder
while the plugin loads

Bug: 375444632
Flag: EXEMPT bugfix
Test: Manually verified using a custom plugin
Change-Id: Ibdf14f6d24adc194a716b29bb75a22220384e730
diff --git a/src/com/android/launcher3/LauncherAppState.java b/src/com/android/launcher3/LauncherAppState.java
index 42a28d6..b6da164 100644
--- a/src/com/android/launcher3/LauncherAppState.java
+++ b/src/com/android/launcher3/LauncherAppState.java
@@ -163,8 +163,7 @@
 
         LockedUserState.get(context).runOnUserUnlocked(() -> {
             CustomWidgetManager cwm = CustomWidgetManager.INSTANCE.get(mContext);
-            cwm.setWidgetRefreshCallback(mModel::refreshAndBindWidgetsAndShortcuts);
-            mOnTerminateCallback.add(() -> cwm.setWidgetRefreshCallback(null));
+            mOnTerminateCallback.add(cwm.addWidgetRefreshCallback(mModel::rebindCallbacks)::close);
 
             IconObserver observer = new IconObserver();
             SafeCloseable iconChangeTracker = mIconProvider.registerIconChangeListener(