Add OWNERS file for provider tests

This is a follow-up to aosp/1521063 to give telephony ownership of
SimPhonebookContractTest but it seemed reasonable to make it more
general and reuse the owners from the production path.

Bug: 154363919
Test: none
Change-Id: I9efd58a5dfeedc19a60a68597984106e4ef8462e
1 file changed