Bug 40011: Hide option for disallowing addons in private mode

components/feature/addons/src/main/res/layout/mozac_feature_addons_fragment_dialog_addon_installed.xml

@@ -63,6 +63,7 @@
         />
 
     <androidx.appcompat.widget.AppCompatCheckBox
+        android:visibility="gone"
         android:id="@+id/allow_in_private_browsing"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"

samples/browser/src/main/res/layout/activity_installed_add_on_details.xml

@@ -70,6 +70,7 @@
                 app:drawableStartCompat="@drawable/mozac_ic_permissions" />
 
         <Switch
+            android:visibility="gone"
             android:id="@+id/allow_in_private_browsing_switch"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"