Modernize CallChipInteractorTest to use Kosmos.Fixture.

This fixes the following error that was happening in presubmit of
If87ed36db184de274587f3d57ad7264c80f1febc:
> FlagSetException: Flag android.app.ui_rich_ongoing set error: This flag was locked when it was read outside of the test code

Fixes: 416338826
Flag: TEST_ONLY
Test: CallChipInteractorTest
Change-Id: I5a37e91523b45fda3e799a5b2ce495141bfc15d2