Remove added categories from .rubocop_todo/rspec/feature_category.yml

A review comment in gitlab-org/gitlab!219647 (comment 3027413672) pointed out that we should remove any added feature_category from the .rubocop_todo/rspec/feature_category.yml file. This task will aim to address that across the work done in the gitlab-org/quality#195 (closed) epic for the new additions