Use Keyset pagination for Groups API by default

This MR introduces Keyset pagination
for Groups API, by default when the user
is unauthenticated

Changelog: added

config/feature_flags/development/keyset_pagination_for_groups_api.yml

----
-name: keyset_pagination_for_groups_api
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/68346
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/339831
-milestone: '14.3'
-type: development
-group: group::access
-default_enabled: false

lib/api/groups.rb

@@ -109,7 +109,7 @@ module API
       end
 
       def present_groups_with_pagination_strategies(params, groups)
-        return present_groups(params, groups) if current_user.present? || Feature.disabled?(:keyset_pagination_for_groups_api)
+        return present_groups(params, groups) if current_user.present?
 
         options = {
           with: Entities::Group,

spec/requests/api/groups_spec.rb

@@ -174,18 +174,6 @@ RSpec.describe API::Groups do
                 'Remaining records can be retrieved using keyset pagination.'
               )
             end
-
-            context 'when the feature flag `keyset_pagination_for_groups_api` is disabled' do
-              before do
-                stub_feature_flags(keyset_pagination_for_groups_api: false)
-              end
-
-              it 'returns successful response' do
-                get api('/groups'), params: { page: 3000, per_page: 25 }
-
-                expect(response).to have_gitlab_http_status(:ok)
-              end
-            end
           end
 
           context 'on making requests below the allowed offset pagination threshold' do
@@ -247,24 +235,6 @@ RSpec.describe API::Groups do
               expect(records.size).to eq(1)
               expect(records.first['id']).to eq(group_2.id)
             end
-
-            context 'when the feature flag `keyset_pagination_for_groups_api` is disabled' do
-              before do
-                stub_feature_flags(keyset_pagination_for_groups_api: false)
-              end
-
-              it 'ignores the keyset pagination params and performs offset pagination' do
-                get api('/groups'), params: { pagination: 'keyset', per_page: 1 }
-
-                expect(response).to have_gitlab_http_status(:ok)
-                records = json_response
-                expect(records.size).to eq(1)
-                expect(records.first['id']).to eq(group_1.id)
-
-                params_for_next_page = params_for_next_page(response)
-                expect(params_for_next_page).not_to include('cursor')
-              end
-            end
           end
 
           context 'on making requests with unsupported ordering structure' do