[BUGFIX lts] Remove all own listeners

[pzuraq]

We were previously only removing own listeners if they were functions,
this PR updates us to always remove all of them.

Fixes #18140

[rwjblue]

Changes seem generally good, but we really need to get a regression test in here too I think...

[rwjblue]

Thank you!

[BillyRayPreachersSon]

Will this fix be backported to Ember 3.8, so that LTS users get the benefit? This is really hampering us upgrading from 3.4 LTS, as the memory usage in our app goes through the roof (in one test alone, the retained memory goes from 1.5MB under Ember 3.4 to around 35MB under Ember 3.8).

For our Ember setup (ember-cli 3.8.3 with ember-source 3.8.2), removing the function check from ember.prod.js and ember.debug.js in our node_modules/ember-source/dist/ and node_modules/ember-source/dist/legacy/ folders fixes the memory leaks in the tests, so it's definitely looking good for us.

Thanks!

[pzuraq]

The fix is marked for LTS releases, so yes, it will.