Don't clear calling identity before setCeStorageProtection()

Now that http://ag/34834390 has moved
IStorageManager#setCeStorageProtection() to
StorageManagerInternal#setCeStorageProtection(), it no longer requires
the STORAGE_INTERNAL permission.  Therefore, it is no longer necessary
for LockSettingsService#setCeStorageProtection() to clear and restore
the calling identity.

(It may have been unnecessary even before that CL, since the callers of
LockSettingsService#setCeStorageProtection() should have already had a
cleared calling identity anyway.)

Bug: 434738842
Flag: EXEMPT refactor
Test: atest FrameworksServicesTests:com.android.server.locksettings
Change-Id: I5ad7fb8ef5f84cc67a2bd8b49d4124d57f8f6b97