In new PK settings don't set Keyboard layout before device added

getKeyboardLayoutOverlay() native callback can occur before input
device added. But, in new PK settings, set the keyboard layout to
default until we get onInputDeviceAdded() callback.
This is because in new settings we require information like
language tag abd layout type which is only available after device
is fully added.

Keep the Old settings behavior as-is since it doesn't use extra
information of language tag and layout type.

Test: manual
Bug: 271499078
Change-Id: I6ea504e3df7928c1dbed5a2e436e3a410c38e350