Use isCeStorageUnlocked() in AppDataRollbackHelper

isUserKeyUnlocked() is being renamed to isCeStorageUnlocked() to make it
clear what it does (considering that there are many types of user keys).
Temporarily, the method exists under both names.  Change
AppDataRollbackHelper to use the new name.  No change in behavior.

Bug: 306204742
Flag: exempt, mechanical refactoring
Test: presubmit
Change-Id: Iab2ca2fdd968bd10dc6e67424d61b21ab66922ea

services/core/java/com/android/server/rollback/AppDataRollbackHelper.java

@@ -266,10 +266,10 @@ public class AppDataRollbackHelper {
     }
 
     /**
-     * @return {@code true} iff. {@code userId} is locked on an FBE device.
+     * @return {@code true} iff the credential-encrypted storage for {@code userId} is locked.
      */
     @VisibleForTesting
     public boolean isUserCredentialLocked(int userId) {
-        return StorageManager.isFileEncrypted() && !StorageManager.isUserKeyUnlocked(userId);
+        return StorageManager.isFileEncrypted() && !StorageManager.isCeStorageUnlocked(userId);
     }
 }