Move migrations to post_migrate

- bump docs to 13.2
- remove unneeded spec

doc/user/project/labels.md

@@ -259,7 +259,7 @@ Ties are broken arbitrarily.
 In specific circumstances it was possible to create labels with duplicate titles in the same
 namespace.
 
-To resolve the duplication, [in GitLab 13.1](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/21384)
+To resolve the duplication, [in GitLab 13.2](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/21384)
 and later, some duplicate labels have `_duplicate<number>` appended to their titles.
 
 You can safely change these labels' titles if you prefer.

spec/migrations/remove_duplicate_labels_from_project_spec.rb

 # frozen_string_literal: true
 
 require 'spec_helper'
-require Rails.root.join('db', 'migrate', '20200305082754_remove_duplicate_labels_from_project.rb')
+require Rails.root.join('db', 'post_migrate', '20200305082754_remove_duplicate_labels_from_project.rb')
 
-describe RemoveDuplicateLabelsFromProject do
+RSpec.describe RemoveDuplicateLabelsFromProject do
   let(:labels_table) { table(:labels) }
   let(:labels) { labels_table.all }
   let(:projects_table) { table(:projects) }

spec/services/incident_management/create_incident_label_service_spec.rb

@@ -54,29 +54,5 @@ RSpec.describe IncidentManagement::CreateIncidentLabelService do
     context 'without label' do
       it_behaves_like 'new label'
     end
-
-    context 'with duplicate labels', issue: 'https://gitlab.com/gitlab-org/gitlab-foss/issues/65042' do
-      before do
-        # Replicate race condition to create duplicates
-        build(:label, project: project, title: title).save!(validate: false)
-        build(:label, project: project, title: title).save!(validate: false)
-      end
-
-      it 'create an issue without labels' do
-        # Verify we have duplicates
-        expect(project.labels.size).to eq(2)
-        expect(project.labels.map(&:title)).to all(eq(title))
-
-        message = <<~MESSAGE.chomp
-          Cannot create incident label "incident" \
-          for "#{project.full_name}": Title has already been taken.
-        MESSAGE
-
-        expect(service).to receive(:log_info).with(message)
-        expect(execute).to be_error
-        expect(execute.payload[:label]).to be_kind_of(Label)
-        expect(execute.message).to eq('Title has already been taken')
-      end
-    end
   end
 end