Simple bypass to allow APs to be unitless with unitful connections

[cmhyett]

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

Should close #3842, albeit with a solution for a different problem than stated there originally.