Docs: Remove all remaining orphaned images.

doc/user/admin_area/settings/img/group_settings.png

doc/user/group/img/group_issue_board.png

doc/user/group/img/new_group_form.png

doc/user/project/img/assignee_lists.png

doc/user/project/img/issue_board.png

doc/user/project/img/labels_sidebar_inline.png

doc/user/project/img/priority_sort_order.png

doc/user/project/img/project_security_dashboard.png

doc/user/project/img/protected_branches_choose_branch.png

doc/user/project/img/protected_branches_error_ui.png

...rt/img/import_projects_from_github_select_auth_method.png

doc/user/project/integrations/img/jira_project_name.png

doc/user/project/integrations/img/jira_service.png

doc/user/project/integrations/img/prometheus_yaml_deploy.png

doc/user/project/issues/img/group_issues_list_view.png

doc/user/project/issues/img/issue_template.png

.../project/members/img/add_new_user_to_project_settings.png

doc/user/project/members/img/add_user_members_menu.png

doc/user/project/members/img/max_access_level.png

doc/user/project/pages/img/pages_create_project.png