Replace `flash` imports to `alert` - 15/36

...ts/javascripts/analytics/cycle_analytics/store/actions.js

...ipts/analytics/shared/components/value_stream_metrics.vue

...cripts/analytics/usage_trends/components/usage_counts.vue

app/assets/javascripts/awards_handler.js

app/assets/javascripts/badges/components/badge_form.vue

app/assets/javascripts/badges/components/badge_settings.vue

app/assets/javascripts/diff.js

...itor/extensions/source_editor_markdown_livepreview_ext.js

...sets/javascripts/error_tracking_settings/store/actions.js

...javascripts/feature_highlight/feature_highlight_helper.js

app/assets/javascripts/gpg_badges.js

app/assets/javascripts/group.js

...vascripts/merge_conflicts/components/diff_file_editor.vue

app/assets/javascripts/merge_conflicts/store/actions.js

...vascripts/audit_events/components/audit_events_stream.vue

...avascripts/audit_events/components/stream/stream_item.vue

...it_events/components/tokens/shared/audit_filter_token.vue

...ts/javascripts/maintenance_mode_settings/store/actions.js

...components/health_status/sidebar_health_status_widget.vue

...ripts/sidebar/components/weight/sidebar_weight_widget.vue