Use separate container for ContactsUnavailableFragment

Having 2 fragments in the same container view was causing issues
with the fragment back stack on older API levels when navigating in
suggestions screen.

Test
manually verified that navigation works as expected when the contacts
list is empty on API 22 and 23 emulators

Bug 32621879
Change-Id: I77d5accd822edfcf5ef1c3a50c0e3d3cdbe508ae