Cleaned up launch complete behavior on dashboard

no issue

- when switching from the user-specific `feature.launchComplete` flag to the global `settings.editorIsLaunchComplete` there was a missed replacement of `feature`->`settings` in the dashboard logic for showing "start creating content" CTA, resulting in it being always shown
- removes `launchComplete` feature flag setup on user which was used earlier for launch complete behavior

ghost/admin/app/services/feature.js

@@ -51,7 +51,6 @@ export default Service.extend({
 
     emailAnalytics: feature('emailAnalytics'),
     nightShift: feature('nightShift', {user: true, onChange: '_setAdminTheme'}),
-    launchComplete: feature('launchComplete', {user: true}),
     multipleProducts: feature('multipleProducts'),
     oauthLogin: feature('oauthLogin', {developer: true}),
     customThemeSettings: feature('customThemeSettings'),

ghost/admin/app/templates/dashboard.hbs

@@ -137,7 +137,7 @@
 
 
         <section class="gh-dashboard-area mixed">
-            {{#if (not this.feature.launchComplete)}}
+            {{#if (not this.settings.editorIsLaunchComplete)}}
             <div class="gh-dashboard-container start-contents">
                 <div class="gh-dashboard-box blogpost">
                     <h2>Start creating content</h2>