[nancy][grappe] max_walltime update

...grid5000/sites/nancy/clusters/grappe/nodes/grappe-10.json

...grid5000/sites/nancy/clusters/grappe/nodes/grappe-11.json

...grid5000/sites/nancy/clusters/grappe/nodes/grappe-12.json

...grid5000/sites/nancy/clusters/grappe/nodes/grappe-13.json

...grid5000/sites/nancy/clusters/grappe/nodes/grappe-14.json

...grid5000/sites/nancy/clusters/grappe/nodes/grappe-15.json

...grid5000/sites/nancy/clusters/grappe/nodes/grappe-16.json

.../grid5000/sites/nancy/clusters/grappe/nodes/grappe-5.json

.../grid5000/sites/nancy/clusters/grappe/nodes/grappe-6.json

.../grid5000/sites/nancy/clusters/grappe/nodes/grappe-7.json

.../grid5000/sites/nancy/clusters/grappe/nodes/grappe-8.json

.../grid5000/sites/nancy/clusters/grappe/nodes/grappe-9.json

input/grid5000/sites/nancy/clusters/grappe/grappe.yaml