Remove widespread use of ns-type=simple in tests

DD requires ns-type=grid, so any test case large enough to run on more
than one rank needs ns-type=grid. There was already a test for
ns-type=simple and Verlet; this commit adds one for group.

For the record, all the tests passed (single and double) with just
changing the grompp.mdp files and gmxtest.pl (most still passed with
-tight, too). However, they've been regenerated for posterity.

Change-Id: I5af213bc262e351b709b59a1247b07af6b1a290f