Add latest changes from gitlab-org/gitlab@master

doc/development/event_tracking/frontend.md

doc/user/project/pages/index.md

doc/user/project/pipelines/settings.md

lib/gitlab/project_template.rb

locale/gitlab.pot

spec/features/projects/environments/environments_spec.rb

spec/frontend/confirm_modal_spec.js

spec/frontend/lib/utils/datetime_utility_spec.js

spec/frontend/vue_shared/components/confirm_modal_spec.js

spec/lib/gitlab/project_template_spec.rb

spec/requests/api/graphql_spec.rb

spec/requests/api/group_boards_spec.rb

spec/requests/api/group_clusters_spec.rb

spec/requests/api/group_export_spec.rb

spec/requests/api/group_import_spec.rb

spec/requests/api/group_labels_spec.rb

spec/requests/api/group_variables_spec.rb

spec/requests/api/groups_spec.rb

spec/requests/api/helpers_spec.rb

spec/requests/api/import_github_spec.rb