Allow the LockPatterUtils to be null

In some tests it could inconsistently become a null, crashing with NPE, for the reason I can't understand (maybe there is a race condition somewhere between mocking and accessing the LockPatterUtils in such tests)
Let's accept it gracefully

Test: atest SettingsUnitTests
Bug: 382637173
Flag: EXEMPT bugfix
Change-Id: I35d5faa1a29307fc780207a816680a32b2796bc0