Remove AutoMTK constructor overload here

[Vaibhavdixit02]

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API

Additional context

Depends on SciML/ADTypes.jl#61

Fixes #55

[gdalle]

AutoModelingToolkit is deprecated so I think the solution is to avoid relying on it altogether, not reintroduce it in ADTypes

[ChrisRackauckas]

Well we should make the deprecation path actually correct. The issue is that the deprecation is not correct.

[ChrisRackauckas]

Deprecation paths are all working here! Lots of work to be done, but that's a big win.