Refactor PersistentUserCallout instantiations

Uses a new factory method to DRY instantiation.

app/assets/javascripts/clusters/clusters_bundle.js

@@ -119,8 +119,7 @@ export default class Clusters {
 
   static initDismissableCallout() {
     const callout = document.querySelector('.js-cluster-security-warning');
-
-    if (callout) new PersistentUserCallout(callout); // eslint-disable-line no-new
+    PersistentUserCallout.factory(callout);
   }
 
   addListeners() {

app/assets/javascripts/pages/groups/clusters/index/index.js

@@ -2,6 +2,5 @@ import PersistentUserCallout from '~/persistent_user_callout';
 
 document.addEventListener('DOMContentLoaded', () => {
   const callout = document.querySelector('.gcp-signup-offer');
-
-  if (callout) new PersistentUserCallout(callout); // eslint-disable-line no-new
+  PersistentUserCallout.factory(callout);
 });

app/assets/javascripts/pages/groups/index.js

@@ -3,8 +3,7 @@ import initGkeDropdowns from '~/projects/gke_cluster_dropdowns';
 
 function initGcpSignupCallout() {
   const callout = document.querySelector('.gcp-signup-offer');
-
-  if (callout) new PersistentUserCallout(callout); // eslint-disable-line no-new
+  PersistentUserCallout.factory(callout);
 }
 
 document.addEventListener('DOMContentLoaded', () => {

app/assets/javascripts/pages/projects/clusters/index/index.js

@@ -2,6 +2,5 @@ import PersistentUserCallout from '~/persistent_user_callout';
 
 document.addEventListener('DOMContentLoaded', () => {
   const callout = document.querySelector('.gcp-signup-offer');
-
-  if (callout) new PersistentUserCallout(callout); // eslint-disable-line no-new
+  PersistentUserCallout.factory(callout);
 });

app/assets/javascripts/pages/projects/index.js

@@ -13,7 +13,7 @@ document.addEventListener('DOMContentLoaded', () => {
 
   if (newClusterViews.indexOf(page) > -1) {
     const callout = document.querySelector('.gcp-signup-offer');
-    if (callout) new PersistentUserCallout(callout); // eslint-disable-line no-new
+    PersistentUserCallout.factory(callout);
 
     initGkeDropdowns();
   }