Migrating additional system robolectric tests

Migrating BluetoothMacAddressPreferenceControllerTest,
FactoryResetAccountsPreferenceControllerTest,
FactoryResetEntryPreferenceControllerTest, and
LegalPreferenceControllerTest

Bug: 154538140
Bug: 190854846
Test: atest CarSettingsUnitTests
Change-Id: I83090498041ef7306a8f354d590b81d5eb57c328
9 files changed