[bc25] Notifications should not reserve space for nav bar in Dual Shade.

Test: Manually tested by opening and closing the notifications shade on
a foldable device both in a folded and unfolded configuration.
Test: Unit tests build and pass.
Bug: 338009491
Flag: com.android.systemui.dual_shade

Change-Id: I1507c88dbeaa8074ab9866561fa6a0e03dccad36