fix(magnify_ime): Stop magnifying the nav bar with this setting.

Magnifying the nav bar makes it difficult for 3-button navigation users to use the nav bar with muscle memory, since they now need to pan to
find it. This makes the CUJ of using the NavBar accessibility shortcut
to enable/disable magnification very tedious.

This change reverts the TYPE_NAVIGATION_BAR behavior to the
behavior before adding this flagged feature.

Bug: 342509709
Test: atest WindowStateTests
Test: manually observe 3-button nav is not magnified
Flag: com.android.server.accessibility.enable_magnification_magnify_nav_bar_and_ime
Change-Id: Icd42a530315717473cf93706aee625993821122e