gitlab: reduce testing scope of check-gcov

This keeps timing out on gitlab due to some qtests taking a long time.
As this is just ensuring the gcov machinery is working and not
attempting to be comprehensive lets skip qtest in this run.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230630180423.558337-4-alex.bennee@linaro.org>

.gitlab-ci.d/buildtest.yml

@@ -454,7 +454,7 @@ gcov:
     IMAGE: ubuntu2204
     CONFIGURE_ARGS: --enable-gcov
     TARGETS: aarch64-softmmu ppc64-softmmu s390x-softmmu x86_64-softmmu
-    MAKE_CHECK_ARGS: check
+    MAKE_CHECK_ARGS: check-unit check-softfloat
   after_script:
     - cd build
     - gcovr --xml-pretty --exclude-unreachable-branches --print-summary