Update segmented control component in Audit Events

Problem to solve

Audit Events is using a custom <gl-button-group> to simulate the look of the segmented control in /ee/app/assets/javascripts/audit_events/components/date_range_buttons.vue. The segmented control style was recently updated in gitlab-ui gitlab-ui!2429 (merged)

Proposal

Replace the GlButtonGroup with GlSegmentedControl