Remove unused CE storage lock events

Remove ICeStorageLockEventListener and the StorageManagerInternal
methods related to it, since they are no longer used.  Their only user
was LockSettingsService, but now LockSettingsService#lockUser() just
incorporates the code that was previously in the callback.

Bug: 389069078
Flag: EXEMPT removing unused code
Test: atest StorageManagerServiceTest
Change-Id: If84b5928d5dea3c8ed42e82d6451fcaea8394f07