Remove unused feature flag YML files

This fixes the rspec:feature-flags job

config/feature_flags/development/packages_and_registries_group_settings.yml

----
-name: packages_and_registries_group_settings
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/51460
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/297371
-milestone: '13.8'
-type: development
-group: group::package
-default_enabled: false

config/feature_flags/development/track_unique_wiki_page_views.yml

----
-name: track_unique_wiki_page_views
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/44622
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/267162
-milestone: '13.5'
-type: development
-group: group::editor
-default_enabled: true