Make simgrid tests faster when debug is not enabled

tests/loader.c

@@ -404,8 +404,10 @@ int main(int argc, char *argv[])
 			launcher_argv[i++] = argv[x++];
 		}
 #ifdef STARPU_SIMGRID
+#ifdef STARPU_DEBUG
 		launcher_argv[i++] = "--cfg=contexts/factory:thread";
 #endif
+#endif
 		launcher_argv[i++] = NULL;
 		execvp(*launcher_argv, launcher_argv);