Update tests for MTK resorting

Some of the tests assumed a value ordering

Author: ChrisRackauckas

test/interface/stiffness_detection_test.jl

@@ -1,8 +1,9 @@
 using OrdinaryDiffEq, Test, ADTypes
-import ODEProblemLibrary: van
+import ODEProblemLibrary: prob_ode_vanderpol
 using ForwardDiff: Dual
 
-prob1 = ODEProblem(van, [0, 2.0], (0.0, 6), inv(0.003))
+sys = prob_ode_vanderpol.f.sys
+prob1 = ODEProblem(sys, [sys.y => 0, sys.x => 2.0], (0.0, 6), [sys.μ => inv(0.003)])
 function __van(du, u, p, t)
     μ = p[1]
     du[1] = μ * ((1 - u[2]^2) * u[1] - u[2])