Remove clear all button in overview for contextual split

* If we start split from allApps or workspace and then go into
workspace, clear all button was previously showing since it's
only hidding via state manager transitions
* Modify the normal Overview LauncherState to provide a split
translation when we are in contextual and have already selected
the first app in split

Fixes: 296006310
Test: Manually started from overview and workspace,
grid tiles look correct, no clear all button
Flags: aconfig com.android.wm.shell.enable_split_contextual

Change-Id: I8630ce7297119392bb0abb07cdb39592eabf129a