Revert "Add HaTS entrypoint for Magnification page"

This reverts commit e2182809.

Reason for revert: This change was reverted to accommodate a design
update. The display of hats has been moved to a menu action, as
detailed in the new design specification ag/32298200.

NO_IFTTT=Revert change

Bug: 380346799
Test: atest ToggleScreenMagnificationPreferenceFragmentTest
Flag: com.android.server.accessibility.enable_low_vision_hats
Change-Id: Ia78b412e6bdbd229f98dabf03e8b9f54c63a7298