[User Switcher] Use Log.e instead of Log.wtf

Log.wtf does not play nicely with atest because it kills the process.
Use Log.e instead.

Bug: 229867034
Test: Run unit tests with AS
Change-Id: Ie0e50d3fb3fcb9ce656b110f82ffde5721f7155f

packages/SystemUI/src/com/android/keyguard/KeyguardSecurityContainer.java

@@ -860,7 +860,7 @@ public class KeyguardSecurityContainer extends FrameLayout {
         private void setupUserSwitcher() {
             final UserRecord currentUser = mUserSwitcherController.getCurrentUserRecord();
             if (currentUser == null) {
-                Log.wtf(TAG, "Current user in user switcher is null.");
+                Log.e(TAG, "Current user in user switcher is null.");
                 return;
             }
             Drawable userIcon = findUserIcon(currentUser.info.id);