Merge branch '196838-remove-routing-ff' into 'master'

Remove elasticsearch_use_routing feature flag

See merge request gitlab-org/gitlab!27398

changelogs/unreleased/196838-remove-routing-ff.yml

+---
+title: Improve Advanced global search performance by using routing
+merge_request: 27398
+author:
+type: performance

ee/lib/elastic/latest/routing.rb

@@ -8,7 +8,6 @@ module Elastic
       ES_ROUTING_MAX_COUNT = 128
 
       def routing_options(options)
-        return {} if Feature.disabled?(:elasticsearch_use_routing)
         return {} if options[:public_and_internal_projects]
 
         ids = if options[:project_id]

ee/spec/lib/elastic/latest/routing_spec.rb

@@ -27,13 +27,6 @@ describe Elastic::Latest::Routing do
   end
 
   describe '#routing_options' do
-    include StubFeatureFlags
-
-    context 'when feature flag is enabled' do
-      before do
-        stub_feature_flags(elasticsearch_use_routing: true)
-      end
-
     it 'returns correct options for project_id' do
       expect(subject.routing_options({ project_id: 1 })).to eq({ routing: 'project_1' })
     end
@@ -70,19 +63,4 @@ describe Elastic::Latest::Routing do
       expect(subject.routing_options({ project_ids: 1.upto(max_count + 1).to_a })).to eq({})
     end
   end
-
-    context 'when feature flag is disabled' do
-      before do
-        stub_feature_flags(elasticsearch_use_routing: false)
-      end
-
-      it 'returns empty hash for project_ids' do
-        expect(subject.routing_options({ project_ids: project_ids })).to eq({})
-      end
-
-      it 'returns empty hash for empty options' do
-        expect(subject.routing_options({})).to eq({})
-      end
-    end
-  end
 end