Fix performance regressions with handheld apps panel.

Theory: We are now rendering the wallpaper and workspace while All
Apps is open. This is causing additional rendering to be done,
leading to dropped frames and other regressions.

Here I remove workspace/hotseat on phones where the panel will
fully cover them anyway. I also remove the depth controller
during the all apps transition.

Using the "debug overdraw" developer setting, I verified that
Workspace and Hotseat are not drawn below the All Apps panel on
handheld.

I ran ABTD on this change and verified the p95 dropped frames
went back to 0.

Bug: 393188362
Bug: 393088056
Test: abtd commands in the bug
Flag: com.android.launcher3.all_apps_sheet_for_handheld
Change-Id: I47287f3356d401a3bd4202e61fd44199855a4a3c