Remove passing an ember-cli project instance to the config function

[bertdeblock]

I suspect (almost) no users will be affected by this.
If someone does run into this, feel free to give me a ping,
and I will try to suggest a proper migration path.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.49%. Comparing base (d3b56f1) to head (b6a1c8c).
Report is 14 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1037   +/-   ##
=======================================
  Coverage   95.49%   95.49%           
=======================================
  Files          21       21           
  Lines         511      511           
=======================================
  Hits          488      488           
  Misses         23       23           

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[kategengler]

👍 It was also undocumented so this may not actually be breaking.