Hide App Chip for smaller app in 90:10 flex split

Bug: 384110883
Test: Tested with both halves made smaller,
large screen and small (phone has other existing bugs).
Lanscape and portrait.
Flag: com.android.wm.shell.enable_flexible_two_app_split

Change-Id: Ib6508c7b3192cc47fc8406cdf68c826bed29de5f