Allow bubble bar to show on phones if the flag is enabled

* Modifies the method to get the height for bubble bar to work
  on phone if the flag is enabled

Flag: com.android.wm.shell.enable_bubble_bar_on_phones
Test: manual - enable bubble bar on phones observe that
               bubble bar is enabled and kinda works
Bug: 394869612
Change-Id: If233c8b97d9c9fb949ce867a291396a7d91b3871