[reims] Network_api - Rename s/gw/gw-reims (refs: #4867)

.../grid5000/sites/reims/clusters/stremi/nodes/stremi-1.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-10.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-11.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-12.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-13.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-14.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-15.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-16.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-17.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-18.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-19.json

.../grid5000/sites/reims/clusters/stremi/nodes/stremi-2.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-20.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-21.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-22.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-23.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-24.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-25.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-26.json

...grid5000/sites/reims/clusters/stremi/nodes/stremi-27.json