Convert LockSettingsService tests to JUnit4

In preparation for adding more tests to LockSettingsService, convert the
existing JUnit3 tests to JUnit4 like the tests in the
recoverablekeystore subdirectory.

Test: atest FrameworksServicesTests:CachedSyntheticPasswordTests \
            FrameworksServicesTests:LockSettingsServiceTests \
            FrameworksServicesTests:LockSettingsShellCommandTest \
            FrameworksServicesTests:LockSettingsStorageTests \
            FrameworksServicesTests:LockscreenFrpTest \
            FrameworksServicesTests:PasswordSlotManagerTests \
            FrameworksServicesTests:SP800DeriveTests
Test: atest FrameworksServicesTests:SyntheticPasswordTests \
            FrameworksServicesTests:WeaverBasedSyntheticPasswordTests
Bug: 145144304
Change-Id: Iaf280718d4c28966b60c76dda90a4674a24f26c6