Fixes unit tests for ContactsPreferences

Also, makes PhoneticNameDisplay preference configurable.

Test:
Auotomated test is added to verify PhoneticNameDisplay preference in
ContactPreference.

Manually tested by changing the
config_phonetic_name_display_user_changeable.
False to removed the option from settings.
True to display the option in Settings.

Bug: 35811420
Change-Id: I395ed4a3539c90d8aa1731d1590930481ae31097