Ensure the date and time pickers use the correct modes under HOLO

Adds basic TimePickerDialog constructor tests, since there weren't any.
More TimePickerDialog tests will be added in a later CL, but this is
enough to verify the change in MR1.

Bug: 31586821
Test: passed
Change-Id: Ice2e203983769f1ea1cfa93105eb97b6fa5176b9
8 files changed