Disallow taskbar long click when in split selection state

* This is specifically when contextual is initiated on home
screen and then user swipes up into overview.
* We no longer want to rely on LauncherStates for split specific
management

Bug: 295981634
Test: Start split on home, swipe up to overview, long press on
taskbar app icons, nothing happens
Flag: ENABLE_SPLIT_FROM_WORKSPACE_TO_WORKSPACE

Change-Id: I9e56ddbe1f536be779d4848769a993724d5395da