testsuite: update ramsey_model to new command sequence using ramsey_model

tests/optimal_policy/Ramsey/Gali_commitment.mod

tests/optimal_policy/Ramsey/ramsey_ex_aux.mod

...s/optimal_policy/Ramsey/ramsey_ex_wrong_ss_file_xfail.mod

tests/optimal_policy/Ramsey/ramsey_histval.mod

tests/optimal_policy/Ramsey/ramsey_histval_xfail.mod

tests/optimal_policy/mult_elimination_test.mod

tests/optimal_policy/nk_ramsey.mod

tests/optimal_policy/nk_ramsey_det.mod

tests/optimal_policy/nk_ramsey_expectation.mod

tests/optimal_policy/nk_ramsey_expectation_a.mod

tests/optimal_policy/nk_ramsey_model.mod

tests/optimal_policy/ramsey_.mod