revert r31281, r31992, r31294, because 'property to be solved' should be specified in each Solver portal type itself and we don't need indexed relation between solver decision and solver.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@31305 20353a03-c40f-0410-a6d1-a30d3c3de9de