added AdaptiveRadau and RadauIIA9 to step_limiter_test.jl tests

[cwittens]

Checklist

• [x ] 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

as title says