Changed the number of mpiprocs/walkers in mwalkers tests

regtest/ves/rt-le-1d-mwalkers-restart/config

 plumed_modules=ves
-mpiprocs=3
+mpiprocs=2
 type=driver
-arg="--plumed plumed.dat --trajectory-stride 500 --timestep 0.002 --igro traj.gro --dump-forces forces --dump-forces-fmt=%10.6f --multi 3"
+arg="--plumed plumed.dat --trajectory-stride 500 --timestep 0.002 --igro traj.gro --dump-forces forces --dump-forces-fmt=%10.6f --multi 2"

regtest/ves/rt-le-1d-mwalkers-welltempered-restart/config

 plumed_modules=ves
-mpiprocs=3
+mpiprocs=2
 type=driver
-arg="--plumed plumed.dat --trajectory-stride 500 --timestep 0.002 --igro traj.gro --dump-forces forces --dump-forces-fmt=%10.6f --multi 3 "
+arg="--plumed plumed.dat --trajectory-stride 500 --timestep 0.002 --igro traj.gro --dump-forces forces --dump-forces-fmt=%10.6f --multi 2 "

regtest/ves/rt-le-1d-mwalkers/config

 plumed_modules=ves
-mpiprocs=3
+mpiprocs=2
 type=driver
-arg="--plumed plumed.dat --trajectory-stride 500 --timestep 0.002 --igro traj.gro --dump-forces forces --dump-forces-fmt=%10.6f --multi 3 "
+arg="--plumed plumed.dat --trajectory-stride 500 --timestep 0.002 --igro traj.gro --dump-forces forces --dump-forces-fmt=%10.6f --multi 2 "