Remove issue_suggestions feature flag

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/55166

app/assets/javascripts/pages/projects/issues/form.js

@@ -17,7 +17,7 @@ export default () => {
   new MilestoneSelect();
   new IssuableTemplateSelectors();
 
-  if (gon.features.issueSuggestions && gon.features.graphql) {
+  if (gon.features.graphql) {
     initSuggestions();
   }
 };

app/controllers/graphql_controller.rb

@@ -43,6 +43,6 @@ class GraphqlController < ApplicationController
   end
 
   def check_graphql_feature_flag!
-    render_404 unless Feature.enabled?(:graphql)
+    render_404 unless Feature.enabled?(:graphql, default_enabled: true)
   end
 end

app/controllers/projects/issues_controller.rb

@@ -268,7 +268,6 @@ class Projects::IssuesController < Projects::ApplicationController
   end
 
   def set_suggested_issues_feature_flags
-    push_frontend_feature_flag(:graphql)
-    push_frontend_feature_flag(:issue_suggestions)
+    push_frontend_feature_flag(:graphql, default_enabled: true)
   end
 end

app/views/shared/issuable/_form.html.haml

@@ -17,7 +17,7 @@
 
   = render 'shared/issuable/form/template_selector', issuable: issuable
   = render 'shared/issuable/form/title', issuable: issuable, form: form, has_wip_commits: commits && commits.detect(&:work_in_progress?)
-- if Feature.enabled?(:issue_suggestions) && Feature.enabled?(:graphql)
+- if Feature.enabled?(:graphql, default_enabled: true)
   #js-suggestions{ data: { project_path: @project.full_path } }
 
 = render 'shared/form_elements/description', model: issuable, form: form, project: project