Update dependency @gitlab/ui to v21.4.2

...nts/__snapshots__/audit_events_export_button_spec.js.snap

...ts/__snapshots__/merge_commits_export_button_spec.js.snap

...omponents/__snapshots__/dependencies_actions_spec.js.snap

...dashboard/components/__snapshots__/dashboard_spec.js.snap

...oard/components/__snapshots__/project_header_spec.js.snap

..._snapshots__/project_adjourned_delete_button_spec.js.snap

...us_page_settings/__snapshots__/settings_form_spec.js.snap

...ts/policy_editor/__snapshots__/policy_editor_spec.js.snap

package.json

...ents/__snapshots__/add_context_commits_modal_spec.js.snap

...t_settings/__snapshots__/alert_settings_form_spec.js.snap

..._navigation/components/__snapshots__/popover_spec.js.snap

...ents/toolbar/__snapshots__/design_navigation_spec.js.snap

...ement/components/toolbar/__snapshots__/index_spec.js.snap

...ement/components/upload/__snapshots__/button_spec.js.snap

.../design_management/pages/__snapshots__/index_spec.js.snap

..._management/pages/design/__snapshots__/index_spec.js.snap

...components/__snapshots__/grafana_integration_spec.js.snap

...ettings/components/__snapshots__/alerts_form_spec.js.snap

...onents/__snapshots__/incidents_settings_tabs_spec.js.snap