Adds dropdown

Fixed HTML

app/views/projects/clusters/_dropdown.html.haml

+%h4.prepend-top-0= s_('ClusterIntegration|Choose how to set up cluster integration')
+
+.dropdown
+  %button.dropdown-toggle.form-control{ type: 'button', data: { toggle: 'dropdown' }, "aria-haspopup": true, "aria-expanded": false }
+    = dropdown_text
+    %span.caret
+  %ul.dropdown-menu
+    %li
+      %a{ href: providers_gcp_new_namespace_project_clusters_path(@project.namespace, @project) }
+        = s_('ClusterIntegration| Create cluster on Google Engine')
+    %li
+      %a{ href: platforms_kubernetes_new_namespace_project_clusters_path(@project.namespace, @project)}
+        = s_('ClusterIntegration| Add existing cluster')

app/views/projects/clusters/_header.html.haml

-%h4.prepend-top-0
-  = s_('ClusterIntegration|Create new cluster on Google Container Engine')
+%h4
+  = s_('ClusterIntegration|Enter the details for your cluster')
 %p
   = s_('ClusterIntegration|Please make sure that your Google account meets the following requirements:')
 %ul

app/views/projects/clusters/gcp/_form.html.haml

-.row
-  .col-sm-8.col-sm-offset-4
-    %p
-      - link_to_help_page = link_to(s_('ClusterIntegration|help page'), help_page_path('user/project/clusters/index'), target: '_blank', rel: 'noopener noreferrer')
-      = s_('ClusterIntegration|Read our %{link_to_help_page} on cluster integration.').html_safe % { link_to_help_page: link_to_help_page}
 
-      = form_for @cluster, url: providers_gcp_namespace_project_clusters_path(@project.namespace, @project), as: :cluster do |field|
+= form_for @cluster, url: providers_gcp_namespace_project_clusters_path(@project.namespace, @project), as: :cluster do |field|
   = form_errors(@cluster)
   .form-group
     = field.label :name, s_('ClusterIntegration|Cluster name')

app/views/projects/clusters/gcp/new.html.haml

@@ -5,6 +5,6 @@
   .col-sm-4
     = render 'projects/clusters/sidebar'
   .col-sm-8
+    = render 'projects/clusters/dropdown', dropdown_text: s_('ClusterIntegration|Create cluster on Google Container Engine')
     = render 'projects/clusters/header'
-
-= render 'form'
+    = render 'form'

app/views/projects/clusters/kubernetes/_form.html.haml

-.row
-  .col-sm-8.col-sm-offset-4
-    %p
-      - link_to_help_page = link_to(s_('ClusterIntegration|help page'), help_page_path('user/project/clusters/index'), target: '_blank', rel: 'noopener noreferrer')
-      = s_('ClusterIntegration|Read our %{link_to_help_page} on cluster integration.').html_safe % { link_to_help_page: link_to_help_page}
-
-      = form_for @cluster, url: platforms_kubernetes_namespace_project_clusters_path(@project.namespace, @project), as: :cluster do |field|
+= form_for @cluster, url: platforms_kubernetes_namespace_project_clusters_path(@project.namespace, @project), as: :cluster do |field|
   = form_errors(@cluster)
   .form-group
     = field.label :name, s_('ClusterIntegration|Cluster name')

app/views/projects/clusters/kubernetes/new.html.haml

@@ -5,6 +5,6 @@
   .col-sm-4
     = render 'projects/clusters/sidebar'
   .col-sm-8
+    = render 'projects/clusters/dropdown', dropdown_text: s_('ClusterIntegration|Add existing cluster')
     = render 'projects/clusters/header'
-
-= render 'form'
+    = render 'form'