Add reliable tag to issue board e2e specs

qa/qa/specs/features/ee/browser_ui/2_plan/issue_boards/configurable_issue_board_spec.rb

 # frozen_string_literal: true
 
 module QA
-  RSpec.describe 'Plan' do
+  RSpec.describe 'Plan', :reliable do
     describe 'Configurable issue board' do
       let(:label_board_list) do
         EE::Resource::Board::BoardList::Project::LabelBoardList.fabricate_via_api!

qa/qa/specs/features/ee/browser_ui/2_plan/issue_boards/configure_issue_board_by_label_spec.rb

 # frozen_string_literal: true
 
 module QA
-  RSpec.describe 'Plan' do
+  RSpec.describe 'Plan', :reliable do
     describe 'Configure issue board by label' do
       let(:label_board_list) do
         EE::Resource::Board::BoardList::Project::LabelBoardList.fabricate_via_api!

qa/qa/specs/features/ee/browser_ui/2_plan/issue_boards/create_group_issue_board_spec.rb

@@ -3,7 +3,7 @@
 require 'securerandom'
 
 module QA
-  RSpec.describe 'Plan' do
+  RSpec.describe 'Plan', :reliable do
     describe 'Group issue boards' do
       before do
         Flow::Login.sign_in

qa/qa/specs/features/ee/browser_ui/2_plan/issue_boards/read_only_board_configuration_spec.rb

 # frozen_string_literal: true
 
 module QA
-  RSpec.describe 'Plan' do
+  RSpec.describe 'Plan', :reliable do
     describe 'Read-only board configuration' do
       let(:qa_user) do
         Resource::User.fabricate_or_use(Runtime::Env.gitlab_qa_username_1, Runtime::Env.gitlab_qa_password_1)

qa/qa/specs/features/ee/browser_ui/2_plan/issue_boards/sum_of_issues_weights_spec.rb

 # frozen_string_literal: true
 
 module QA
-  RSpec.describe 'Plan' do
+  RSpec.describe 'Plan', :reliable do
     describe 'Sum of issues weights on issue board' do
       let(:label_board_list) do
         EE::Resource::Board::BoardList::Project::LabelBoardList.fabricate_via_api!