Deprecation warning violates `ember test --silent` behavior

[nragaz]

According to the help for ember test:

--silent (Boolean) (Default: false) Suppress any output except for the test report

But the deprecation warning DEPRECATION: Overriding init without calling this._super is deprecated. Please call this._super() busts through that flag, breaking an automated CI workflow (because the CI output now includes these deprecation warnings instead of being only the test results).