Replace let with let_it_be

- Reduce DB queries by using let_it_be helper

spec/features/boards/boards_spec.rb

@@ -6,11 +6,11 @@ RSpec.describe 'Issue Boards', :js do
   include DragTo
   include MobileHelpers
 
-  let(:group) { create(:group, :nested) }
-  let(:project) { create(:project, :public, namespace: group) }
-  let(:board)   { create(:board, project: project) }
-  let(:user)    { create(:user) }
-  let!(:user2)  { create(:user) }
+  let_it_be(:group)   { create(:group, :nested) }
+  let_it_be(:project) { create(:project, :public, namespace: group) }
+  let_it_be(:board)   { create(:board, project: project) }
+  let_it_be(:user)    { create(:user) }
+  let_it_be(:user2)   { create(:user) }
 
   before do
     project.add_maintainer(user)
@@ -62,30 +62,30 @@ RSpec.describe 'Issue Boards', :js do
   end
 
   context 'with lists' do
-    let(:milestone) { create(:milestone, project: project) }
-
-    let(:planning)    { create(:label, project: project, name: 'Planning', description: 'Test') }
-    let(:development) { create(:label, project: project, name: 'Development') }
-    let(:testing)     { create(:label, project: project, name: 'Testing') }
-    let(:bug)         { create(:label, project: project, name: 'Bug') }
-    let!(:backlog)    { create(:label, project: project, name: 'Backlog') }
-    let!(:closed)       { create(:label, project: project, name: 'Closed') }
-    let!(:accepting) { create(:label, project: project, name: 'Accepting Merge Requests') }
-    let!(:a_plus) { create(:label, project: project, name: 'A+') }
-    let!(:list1) { create(:list, board: board, label: planning, position: 0) }
-    let!(:list2) { create(:list, board: board, label: development, position: 1) }
-
-    let!(:confidential_issue) { create(:labeled_issue, :confidential, project: project, author: user, labels: [planning], relative_position: 9) }
-    let!(:issue1) { create(:labeled_issue, project: project, title: 'aaa', description: '111', assignees: [user], labels: [planning], relative_position: 8) }
-    let!(:issue2) { create(:labeled_issue, project: project, title: 'bbb', description: '222', author: user2, labels: [planning], relative_position: 7) }
-    let!(:issue3) { create(:labeled_issue, project: project, title: 'ccc', description: '333', labels: [planning], relative_position: 6) }
-    let!(:issue4) { create(:labeled_issue, project: project, title: 'ddd', description: '444', labels: [planning], relative_position: 5) }
-    let!(:issue5) { create(:labeled_issue, project: project, title: 'eee', description: '555', labels: [planning], milestone: milestone, relative_position: 4) }
-    let!(:issue6) { create(:labeled_issue, project: project, title: 'fff', description: '666', labels: [planning, development], relative_position: 3) }
-    let!(:issue7) { create(:labeled_issue, project: project, title: 'ggg', description: '777', labels: [development], relative_position: 2) }
-    let!(:issue8) { create(:closed_issue, project: project, title: 'hhh', description: '888') }
-    let!(:issue9) { create(:labeled_issue, project: project, title: 'iii', description: '999', labels: [planning, testing, bug, accepting], relative_position: 1) }
-    let!(:issue10) { create(:labeled_issue, project: project, title: 'issue +', description: 'A+ great issue', labels: [a_plus]) }
+    let_it_be(:milestone) { create(:milestone, project: project) }
+
+    let_it_be(:planning)    { create(:label, project: project, name: 'Planning', description: 'Test') }
+    let_it_be(:development) { create(:label, project: project, name: 'Development') }
+    let_it_be(:testing)     { create(:label, project: project, name: 'Testing') }
+    let_it_be(:bug)         { create(:label, project: project, name: 'Bug') }
+    let_it_be(:backlog)     { create(:label, project: project, name: 'Backlog') }
+    let_it_be(:closed)      { create(:label, project: project, name: 'Closed') }
+    let_it_be(:accepting)   { create(:label, project: project, name: 'Accepting Merge Requests') }
+    let_it_be(:a_plus)      { create(:label, project: project, name: 'A+') }
+    let_it_be(:list1)       { create(:list, board: board, label: planning, position: 0) }
+    let_it_be(:list2)       { create(:list, board: board, label: development, position: 1) }
+
+    let_it_be(:confidential_issue) { create(:labeled_issue, :confidential, project: project, author: user, labels: [planning], relative_position: 9) }
+    let_it_be(:issue1) { create(:labeled_issue, project: project, title: 'aaa', description: '111', assignees: [user], labels: [planning], relative_position: 8) }
+    let_it_be(:issue2) { create(:labeled_issue, project: project, title: 'bbb', description: '222', author: user2, labels: [planning], relative_position: 7) }
+    let_it_be(:issue3) { create(:labeled_issue, project: project, title: 'ccc', description: '333', labels: [planning], relative_position: 6) }
+    let_it_be(:issue4) { create(:labeled_issue, project: project, title: 'ddd', description: '444', labels: [planning], relative_position: 5) }
+    let_it_be(:issue5) { create(:labeled_issue, project: project, title: 'eee', description: '555', labels: [planning], milestone: milestone, relative_position: 4) }
+    let_it_be(:issue6) { create(:labeled_issue, project: project, title: 'fff', description: '666', labels: [planning, development], relative_position: 3) }
+    let_it_be(:issue7) { create(:labeled_issue, project: project, title: 'ggg', description: '777', labels: [development], relative_position: 2) }
+    let_it_be(:issue8) { create(:closed_issue, project: project, title: 'hhh', description: '888') }
+    let_it_be(:issue9) { create(:labeled_issue, project: project, title: 'iii', description: '999', labels: [planning, testing, bug, accepting], relative_position: 1) }
+    let_it_be(:issue10) { create(:labeled_issue, project: project, title: 'issue +', description: 'A+ great issue', labels: [a_plus]) }
 
     before do
       visit project_board_path(project, board)
@@ -636,7 +636,7 @@ RSpec.describe 'Issue Boards', :js do
   end
 
   context 'as guest user' do
-    let(:user_guest) { create(:user) }
+    let_it_be(:user_guest) { create(:user) }
 
     before do
       project.add_guest(user_guest)