tst_Q*Application::runHelperTest(): Run test without activating app on macOS

As that will steal focus from tst_QApplication, which is needed for
subsequent tests.

Pick-to: 6.8 6.9
Change-Id: I5720c4a2bb45f98894616e01da10b9c40a2b6735
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

tests/auto/corelib/kernel/qcoreapplication/apphelper.cpp

@@ -131,6 +131,9 @@ int main(int argc, char **argv)
     // "+[IMKClient subclass]: chose IMKClient_Legacy"
     if (QOperatingSystemVersion::current() >= QOperatingSystemVersion::MacOSSequoia)
         qputenv("CFLOG_FORCE_DISABLE_STDERR", "1");
+
+    // Don't steal app focus from main test
+    qputenv("QT_MAC_DISABLE_FOREGROUND_APPLICATION_TRANSFORM", "1");
 #  endif
 
     std::string_view subtest(argv[1]);