[VnV] Relax epsilons for the IMDC system

examples/gaia/cohesive_channel/vnv_channel_erosion.py

examples/khione/flume_with_slope-t2d/vnv_flume_slope-t2d.py

examples/khione/saint_lawrence-t2d/vnv_saint_lawrence-t2d.py

...tor4_T2D_various-RefLev/vnv_nestor4_T2D_various-RefLev.py

examples/telemac2d/balzano/vnv_balzano.py

examples/telemac2d/balzano/vnv_balzano_full.py

examples/telemac2d/bump/vnv_bumpsub.py

examples/telemac2d/canal/vnv_canal.py

examples/telemac2d/cavity/vnv_cavity.py

examples/telemac2d/cone/vnv_cone.py

examples/telemac2d/dambreak/vnv_ritter_fv.py

examples/telemac2d/dambreak/vnv_stoker.py

examples/telemac2d/donau/vnv_donau.py

examples/telemac2d/flotteurs/vnv_flotteurs.py

examples/telemac2d/gouttedo/vnv_thompson.py

examples/telemac2d/init/vnv_init.py

examples/telemac2d/malpasset/vnv_malpasset.py

examples/telemac2d/mersey/vnv_mersey.py

examples/telemac2d/pildepon/vnv_pildepon.py

examples/telemac2d/riogrande/vnv_riogrande.py