[CST-6152] allow password change only if a challenge is resolved.

dspace-api/src/main/java/org/dspace/authenticate/LDAPAuthentication.java

@@ -752,4 +752,9 @@ public class LDAPAuthentication
         }
         return false;
     }
+
+    @Override
+    public boolean canChangePassword(Context context, String challenge) {
+        return false;
+    }
 }