Rename svg files for convdev to devops score

app/views/instance_statistics/conversational_development_index/_callout.html.haml

@@ -9,5 +9,5 @@
         = _('Introducing Your Conversational Development Index')
       %p
         = _('Your Conversational Development Index gives an overview of how you are using GitLab from a feature perspective. View how you compare with other organizations, discover features you are not using, and learn best practices through blog posts and white papers.')
-    .svg-container.devops
-      = custom_icon('convdev_overview')
+    .svg-container.convdev
+      = custom_icon('dev_ops_score_overview')

app/views/instance_statistics/conversational_development_index/_disabled.html.haml

 .container.devops-empty
   .col-sm-12.justify-content-center.text-center
-    = custom_icon('convdev_no_index')
+    = custom_icon('dev_ops_score_no_index')
     %h4= _('Usage ping is not enabled')
     - if !current_user.admin?
       %p

app/views/instance_statistics/conversational_development_index/_no_data.html.haml

 .container.devops-empty
   .col-sm-12.justify-content-center.text-center
-    = custom_icon('convdev_no_data')
+    = custom_icon('dev_ops_score_no_data')
     %h4= _('Data is still calculating...')
     %p
       = _('In order to gather accurate feature usage data, it can take 1 to 2 weeks to see your index.')