Inconsistent test engine messages when `(module+ test)` is not ran in #lang-based teaching languages

[shhyou]

This is a minor interface issue. The test engine messages are different when the test submodule is not ran by DrRacket.

1. #lang-based language:

   #lang htdp/isl+
   (check-expect 1 1)
   ;; (+ "world")
   

2. In Language -> Choose Language -> Submodules to Run -> Uncheck test"
3. Run the code. The test engine is not ran, so there are no messages.
4. Uncomment (+ "world") and run the code again. This time the output changes to 0 tests passed..

Menu-based teaching languages are not affected by the submodule option.