Since we instantiate a Menu object each time for a given set of
header/items, we don't have a use case of re-populating an existing Menu
with different data (which is what Menu::Start() does).
Test: mmma -j bootable/recovery
Test: Run recovery_unit_test on marlin.
Test: Build and boot into recovery image on angler. Check the UI.
Change-Id: Iaa2ba9d406ebd74c015e43198c17c5335b38df53