A little tidying.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@19511 b5f69653-2bf5-0310-8201-b0dafb8e1405
Force some more tests to be sequential for #2016.

git-svn-id: https://chaste.cs.ox.ac.uk/svn/chaste/trunk@19514 b5f69653-2bf5-0310-8201-b0dafb8e1405