Fix pipeline graph visualization lines disappearing

When the Ci config value changed, the lines that reprensents
needs were disappearing. This commit fixes this problem
but unmounting the graph when switching tab in the
Pipeline Editor component.

Changelog: fixed

app/assets/javascripts/pipeline_editor/components/pipeline_editor_tabs.vue

@@ -114,6 +114,7 @@ export default {
       :empty-message="$options.i18n.empty.visualization"
       :is-empty="isEmpty"
       :is-invalid="isInvalid"
+      :keep-component-mounted="false"
       :title="$options.i18n.tabGraph"
       lazy
       data-testid="visualization-tab"