Increase Done button size to be more accessible for the gesture tutorial

Touch targets have to meet a minimum of 48 dp to meet accessibility
requirements. The Done button in the gesture navigation tutorial menu
was previously too small.

Flag: LEGACY ENABLE_NEW_GESTURE_NAV_TUTORIAL ENABLED
Fixes: 319752098
Test: Opened the gesture tutorial menu in smaller and larger screens.
Change-Id: I7d9b856ad4829e4ffe26a7df00f42e5e4fcf1b2e