Fixed mismatched error message.

src/main/java/org/orekit/rugged/errors/DumpManager.java

@@ -80,7 +80,7 @@ public class DumpManager {
             DUMP.get().deactivate();
             DUMP.set(null);
         } else {
-            throw new RuggedException(RuggedMessages.DEBUG_DUMP_ALREADY_ACTIVE);
+            throw new RuggedException(RuggedMessages.DEBUG_DUMP_NOT_ACTIVE);
         }
     }