Remove the elasticsearch_web_indexing feature flag

ee/app/controllers/admin/elasticsearch_controller.rb

 # frozen_string_literal: true
 
 class Admin::ElasticsearchController < Admin::ApplicationController
-  before_action :check_elasticsearch_web_indexing_feature_flag!
-
-  def check_elasticsearch_web_indexing_feature_flag!
-    render_404 unless Feature.enabled?(:elasticsearch_web_indexing, default_enabled: true)
-  end
-
   # POST
   # Scheduling indexing jobs
   def enqueue_index

ee/app/views/admin/application_settings/_elasticsearch_form.html.haml

@@ -28,7 +28,7 @@
               - unless Gitlab::CurrentSettings.elasticsearch_indexing?
                 .form-text.text-muted
                   = _('Please create an index before enabling indexing')
-              - if Feature.enabled?(:elasticsearch_web_indexing, default_enabled: true) && Gitlab::CurrentSettings.elasticsearch_indexing?
+              - if Gitlab::CurrentSettings.elasticsearch_indexing?
                 .form-text
                   = link_to _('Index all projects'), admin_elasticsearch_enqueue_index_path,
                       class: ['btn', 'btn-success'], method: :post

ee/spec/controllers/admin/elasticsearch_controller_spec.rb

@@ -36,17 +36,5 @@ RSpec.describe Admin::ElasticsearchController do
         expect(response).to redirect_to integrations_admin_application_settings_path(anchor: 'js-elasticsearch-settings')
       end
     end
-
-    context 'when feature is disabled' do
-      it 'does nothing and returns 404' do
-        stub_feature_flags(elasticsearch_web_indexing: false)
-
-        expect(::Elastic::IndexProjectsService).not_to receive(:new)
-
-        post :enqueue_index
-
-        expect(response).to have_gitlab_http_status(:not_found)
-      end
-    end
   end
 end