Reduce allocations in residual function

[visr]

Continuing from #2224:

18.086399 seconds (4.01 M allocations: 3.255 GiB, 2.81% gc time)
17.879659 seconds (2.95 M allocations: 2.949 GiB, 1.69% gc time)

Adding the type assert on the function does the trick. I also go rid of the isdae check because it shouldn't be needed, and I noticed get_dae_uprev leads to runtime dispatch since it is using isdefined(integrator, ...)

There are still more optimizations to be made to backtracking, but good to bag this one already.
I also noticed many extra allocations if concentration = true, we should also look at that.