Improve board factory to create the default backlog/done lists

spec/services/boards/issues/list_service_spec.rb

@@ -13,10 +13,10 @@ describe Boards::Issues::ListService, services: true do
     let(:p2) { create(:label, title: 'P2', project: project, priority: 2) }
     let(:p3) { create(:label, title: 'P3', project: project, priority: 3) }
 
-    let!(:backlog) { create(:backlog_list, board: board) }
+    let!(:backlog) { board.backlog_list }
     let!(:list1)   { create(:list, board: board, label: development, position: 0) }
     let!(:list2)   { create(:list, board: board, label: testing, position: 1) }
-    let!(:done)    { create(:done_list, board: board) }
+    let!(:done)    { board.done_list }
 
     let!(:opened_issue1) { create(:labeled_issue, project: project, labels: [bug]) }
     let!(:opened_issue2) { create(:labeled_issue, project: project, labels: [p2]) }

spec/services/boards/issues/move_service_spec.rb

@@ -10,10 +10,10 @@ describe Boards::Issues::MoveService, services: true do
     let(:development) { create(:label, project: project, name: 'Development') }
     let(:testing)  { create(:label, project: project, name: 'Testing') }
 
-    let!(:backlog) { create(:backlog_list, board: board1) }
+    let!(:backlog) { board1.backlog_list }
     let!(:list1)   { create(:list, board: board1, label: development, position: 0) }
     let!(:list2)   { create(:list, board: board1, label: testing, position: 1) }
-    let!(:done)    { create(:done_list, board: board1) }
+    let!(:done)    { board1.done_list }
 
     before do
       project.team << [user, :developer]

spec/services/boards/lists/move_service_spec.rb

@@ -6,12 +6,12 @@ describe Boards::Lists::MoveService, services: true do
     let(:board)   { create(:board, project: project) }
     let(:user)    { create(:user) }
 
-    let!(:backlog)     { create(:backlog_list, board: board) }
+    let!(:backlog)     { board.backlog_list }
     let!(:planning)    { create(:list, board: board, position: 0) }
     let!(:development) { create(:list, board: board, position: 1) }
     let!(:review)      { create(:list, board: board, position: 2) }
     let!(:staging)     { create(:list, board: board, position: 3) }
-    let!(:done)        { create(:done_list, board: board) }
+    let!(:done)        { board.done_list }
 
     context 'when list type is set to label' do
       it 'keeps position of lists when new position is nil' do