Enable filtering of confidential epics

Filter out confidential epics which user has not access to.

ee/app/finders/epics_finder.rb

@@ -179,7 +179,6 @@ class EpicsFinder < IssuableFinder
   # rubocop: enable CodeReuse/ActiveRecord
 
   def with_confidentiality_access_check(epics, groups)
-    return epics unless Feature.enabled?(:confidential_epics_query, group)
     return epics if can_read_all_epics_in_related_groups?(groups)
 
     epics.not_confidential_or_in_groups(groups_with_confidential_access(groups))

ee/spec/finders/epics_finder_spec.rb

@@ -370,16 +370,6 @@ RSpec.describe EpicsFinder do
               expect(subject).to match_array([base_epic2, public_epic1, public_epic2])
             end
           end
-
-          context 'when confidential_epics_query is disabled' do
-            before do
-              stub_feature_flags(confidential_epics_query: false)
-            end
-
-            it 'returns also confidential epics' do
-              expect(subject).to match_array([base_epic1, base_epic2, public_epic1, public_epic2])
-            end
-          end
         end
 
         context 'with negated labels' do