Fix picker sync test flakes

PickerSyncControllerTest and PickerDataLayerTest weren't running
hermetically because they used different db name and the setup stage
wasn't resetting the correct db.

Now, moved all tests to use the same name and delete the db between
tests instead to clear state. This also ensures any sync/user prefs
are cleared.

Test: atest PickerSyncControllerTest
Bug: 213144765
Bug: 215618964
Change-Id: Ibbcc21f22b8e3ead1b5b38160fec89219730cb72
2 files changed