Convert server unit tests to robolectric (reland)

Convert the server side unit tests to robolectric.

Relanding with removal from TEST_MAPPING since robolectric is not
supported with TEST_MAPPING

Bug: 312521897
Test: atest DeviceLockUnitTests
Change-Id: I581b1df8092348f6198a91ba19bebdf52d15595e
9 files changed