Use helper for feature check in cluster partials

app/helpers/clusters_helper.rb

+module ClustersHelper
+  def has_multiple_clusters?(project)
+    project.feature_available?(:multiple_clusters)
+  end
+end

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

@@ -9,7 +9,7 @@
     = field.text_field :name, class: 'form-control', placeholder: s_('ClusterIntegration|Cluster name')
   .form-group
     = field.label :environment_scope, s_('ClusterIntegration|Environment scope')
-    = field.text_field :environment_scope, class: 'form-control js-select-on-focus', disabled: true, placeholder: s_('ClusterIntegration|Environment scope')
+    = field.text_field :environment_scope, class: 'form-control', readonly: has_multiple_clusters?(@project), placeholder: s_('ClusterIntegration|Environment scope')
 
   = field.fields_for :provider_gcp, @cluster.provider_gcp do |provider_gcp_field|
     .form-group

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

@@ -9,6 +9,10 @@
 = form_for @cluster, url: namespace_project_cluster_path(@project.namespace, @project, @cluster), as: :cluster do |field|
   = form_errors(@cluster)
 
+  .form-group
+    = field.label :environment_scope, s_('ClusterIntegration|Environment scope')
+    = field.text_field :environment_scope, class: 'form-control js-select-on-focus', readonly: has_multiple_clusters?(@project), placeholder: s_('ClusterIntegration|Environment scope')
+
   = field.fields_for :platform_kubernetes, @cluster.platform_kubernetes do |platform_kubernetes_field|
     .form-group
       = platform_kubernetes_field.label :api_url, s_('ClusterIntegration|API URL')

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

@@ -5,7 +5,7 @@
     = field.text_field :name, class: 'form-control', placeholder: s_('ClusterIntegration|Cluster name')
   .form-group
     = field.label :environment_scope, s_('ClusterIntegration|Environment scope')
-    = field.text_field :environment_scope, class: 'form-control js-select-on-focus', disabled: true, placeholder: s_('ClusterIntegration|Environment scope')
+    = field.text_field :environment_scope, class: 'form-control', readonly: has_multiple_clusters?(@project), placeholder: s_('ClusterIntegration|Environment scope')
 
   = field.fields_for :platform_kubernetes, @cluster.platform_kubernetes do |platform_kubernetes_field|
     .form-group

app/views/projects/clusters/user/_show.html.haml

@@ -4,6 +4,10 @@
     = field.label :name, s_('ClusterIntegration|Cluster name')
     = field.text_field :name, class: 'form-control', placeholder: s_('ClusterIntegration|Cluster name')
 
+  .form-group
+    = field.label :environment_scope, s_('ClusterIntegration|Environment scope')
+    = field.text_field :environment_scope, class: 'form-control js-select-on-focus', readonly: has_multiple_clusters?(@project), placeholder: s_('ClusterIntegration|Environment scope')
+
   = field.fields_for :platform_kubernetes, @cluster.platform_kubernetes do |platform_kubernetes_field|
     .form-group
       = platform_kubernetes_field.label :api_url, s_('ClusterIntegration|API URL')