Clear only workspace shortcut / widget related tests

- This ensure hotseat to be populated with default items, so it won't result in an empty taskbar which get stashed in apps
- Workspace needs to be cleared because shortcut / widget dragging won't always work if there are items in workspace. It only happens in test due to the way we drag items.

Fix: 202546679
Test: NexusLauncherTests:com.android.launcher3.ui.widget.RequestPinItemTest
Change-Id: Ib3ded6a685eaa1b169b75fd179c9e29ca4be1e72