Consolidates config_windowOutsetBottom and circular_display_mask_offset

Three phases involved:
phase 1: change all code references to circurlar_display_mask_offset to
config_windowOutsetBottom, and mark circular_display_mask_offset
deprecated.

phase 2: remove circular_display_mask_offset from device overlays

phase 3: remove circular_display_mask_offset symbol and default setting.

Bug:25220421
Change-Id: Ia3f77610dbbb964eb58c6b28f6206799d56c44c2