Removed unused class properties in \Drupal\Tests\field_ui\FunctionalJavascript\ManageFieldsTest

Seems like a good refactor and think we would know it if broke the tests :)

Needs a rebase.

Re based and fixed conflicts. pipeline is green so moving back to NR.

Rebase seems good.

Committed/pushed to 11.x, thanks!

catch → closed merge request !11642

Automatically closed - issue fixed for 2 weeks with no activity.