Make tests single test at a time for Debug.

ci/scripts/test.sh

@@ -4,7 +4,7 @@ set -eo pipefail
 
 cd build
 if [ $SELF_HOST = false ]; then
-    ctest -j 4 --output-on-failure -C $BUILD_TYPE
+    ctest -j 1 --output-on-failure -C $BUILD_TYPE
 else
     sudo cp libsnmallocshim.so libsnmallocshim-checks.so /usr/local/lib/
     ninja clean