Renaming ACCESSIBILITY_FLOATING_MENU_TARGETS to ACCESSIBILITY_GESTURE_TARGETS

For our intended behavior it is more beneficial to have a separate setting for gesture.
Since this setting was not in use yet, there should be no problems renaming it.

Bug: 300303284
Flag: N/A
Test: N/A
Change-Id: Ic2f14a15c1dc2f4e7391e9ce8ca0036998b6d642