Add on call schedule edit/delete tooltip

ee/app/assets/javascripts/oncall_schedules/components/oncall_schedule.vue

 <script>
-import { GlSprintf, GlCard, GlButtonGroup, GlButton, GlModalDirective } from '@gitlab/ui';
+import {
+  GlSprintf,
+  GlCard,
+  GlButtonGroup,
+  GlButton,
+  GlModalDirective,
+  GlTooltipDirective,
+} from '@gitlab/ui';
 import { s__ } from '~/locale';
 import ScheduleTimelineSection from './schedule/components/schedule_timeline_section.vue';
 import DeleteScheduleModal from './delete_schedule_modal.vue';
@@ -10,8 +17,8 @@ import { getFormattedTimezone } from '../utils/common_utils';
 
 export const i18n = {
   scheduleForTz: s__('OnCallSchedules|On-call schedule for the %{tzShort}'),
-  updateScheduleLabel: s__('OnCallSchedules|Edit schedule'),
-  destroyScheduleLabel: s__('OnCallSchedules|Delete schedule'),
+  editScheduleLabel: s__('OnCallSchedules|Edit schedule'),
+  deleteScheduleLabel: s__('OnCallSchedules|Delete schedule'),
 };
 
 export default {
@@ -29,6 +36,7 @@ export default {
   },
   directives: {
     GlModal: GlModalDirective,
+    GlTooltip: GlTooltipDirective,
   },
   props: {
     schedule: {
@@ -57,13 +65,17 @@ export default {
           <gl-button-group>
             <gl-button
               v-gl-modal.updateScheduleModal
+              v-gl-tooltip
+              :title="$options.i18n.editScheduleLabel"
               icon="pencil"
-              :aria-label="$options.i18n.updateScheduleLabel"
+              :aria-label="$options.i18n.editScheduleLabel"
             />
             <gl-button
               v-gl-modal.deleteScheduleModal
+              v-gl-tooltip
+              :title="$options.i18n.deleteScheduleLabel"
               icon="remove"
-              :aria-label="$options.i18n.destroyScheduleLabel"
+              :aria-label="$options.i18n.deleteScheduleLabel"
             />
           </gl-button-group>
         </div>