Restore static instances after test completes

PhoneUtilsTest was using reflection to replace the static sPhones in
PhoneFactory to run the test but did not restore the previous value
after the test completed. This caused the mocked test phone to remain
even after the test completed, causing NPEs and other weird behavior.

Test: atest TeleServicesTest
Bug: 228813515
Change-Id: I1bc6ac4fbf3206bce6741be187598a63798d7f1e
1 file changed