Fix incorrectly sized overlay for unfold animation

Currently we are fetching display info every time before adding an
overlay. Due to some unknown reason some displays are occasionally(1 out of 3 times) missing from the
list of display received from display manager. This resulted in incorrect display layout parameters and hence
incorrectly sized unfold overlay animation.
After this change we will be fetching the list of displays from display manager
only once when the object is initialized.
Fixes: 324386469
Test: Flash build locally to device
* Fold -> Unfold the device multiple times
* Check if unfold animation is occurring with correct size of overlay
Flag: ACONFIG fold_lock_setting_enabled TRUNKFOOD

Change-Id: Icdc028aac49a2da8361c25ee5906bfcd40582ec7