Prevent Taskbar all apps from showing multi instance options

This change makes it so that we don't show any multi instance options in
Taskbar all apps. This matches the behavior from regular All apps.

Fix: 382342931
Test: Long press an app icon in Taskbar all apps and ensure multi
instance options don't show up.
Flag: com.android.launcher3.enable_multi_instance_menu_taskbar

Change-Id: I5322df328ee5484168b96831f32c2023521704e6