Rollout of basic search for epics

This MR removes the `epics_search` feature flag, thus enabling basic
search for epics by default.

config/feature_flags/development/epics_search.yml

----
-name: epics_search
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/42456
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/250317
-group: group::global search
-type: development
-default_enabled: false
\ No newline at end of file

doc/user/search/index.md

@@ -222,6 +222,7 @@ backed by the database and allows searching in:
 - Merge requests
 - Milestones
 - Users
+- Epics (Group only)
 - Code (Project only)
 - Comments (Project only)
 - Commits (Project only)

ee/app/services/ee/search/group_service.rb

@@ -36,7 +36,7 @@ module EE
 
       override :allowed_scopes
       def allowed_scopes
-        return super unless ::Feature.enabled?(:epics_search) && group.feature_available?(:epics)
+        return super unless group.feature_available?(:epics)
 
         strong_memoize(:ee_group_allowed_scopes) do
           super + %w(epics)

ee/changelogs/unreleased/250317-basic-epics-search-rollout.yml

+---
+title: Add basic search for epics
+merge_request: 44269
+author:
+type: added

ee/spec/features/search/user_searches_for_epics_spec.rb

@@ -15,7 +15,6 @@ RSpec.describe 'User searches for epics', :js do
   end
 
   before do
-    stub_feature_flags(epics_search: true)
     stub_licensed_features(epics: true)
 
     group.add_maintainer(user)

ee/spec/services/search/group_service_spec.rb

@@ -235,28 +235,26 @@ RSpec.describe Search::GroupService, :elastic do
 
   describe '#allowed_scopes' do
     context 'epics scope' do
-      where(:feature_enabled, :epics_available, :epics_allowed) do
-        false     | false    | false
-        true      | false    | false
-        false     | true     | false
-        true      | true     | true
-      end
-
-      with_them do
       let(:allowed_scopes) { described_class.new(user, group, {}).allowed_scopes }
 
       before do
-          stub_feature_flags(epics_search: feature_enabled)
         stub_licensed_features(epics: epics_available)
       end
 
-        it 'sets correct allowed_scopes' do
-          if epics_allowed
+      context 'epics available' do
+        let(:epics_available) { true }
+
+        it 'does include epics to allowed_scopes' do
           expect(allowed_scopes).to include('epics')
-          else
-            expect(allowed_scopes).not_to include('epics')
         end
       end
+
+      context 'epics is no available' do
+        let(:epics_available) { false }
+
+        it 'does not include epics to allowed_scopes' do
+          expect(allowed_scopes).not_to include('epics')
+        end
       end
     end
   end