removed old work file

generators/run-g5kchecks/broken_nodes.txt

-graoully-7.nancy.grid5000.fr
-grimoire-2.nancy.grid5000.fr
-graphene-86.nancy.grid5000.fr
-graphene-76.nancy.grid5000.fr
-graphene-80.nancy.grid5000.fr
-graphene-92.nancy.grid5000.fr
-talc-126.nancy.grid5000.fr
-graphene-88.nancy.grid5000.fr
-graphene-82.nancy.grid5000.fr
-grimoire-1.nancy.grid5000.fr
-graphene-83.nancy.grid5000.fr