Fixed unit tests expecting stan::agrad::determinant(matrix_d).
Fixed unit tests expecting stan::agrad::determinant(matrix_d).

stan-dev/stan,stan-dev/stan,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/stan