Remove un-used methods

These two methods were used in emitting AUTO_DEVOPS_DOMAIN which has now
been dropped.

app/models/project_auto_devops.rb

@@ -16,14 +16,6 @@ class ProjectAutoDevops < ApplicationRecord
 
   after_save :create_gitlab_deploy_token, if: :needs_to_create_deploy_token?
 
-  def instance_domain
-    Gitlab::CurrentSettings.auto_devops_domain
-  end
-
-  def has_domain?
-    domain.present? || instance_domain.present?
-  end
-
   def predefined_variables
     Gitlab::Ci::Variables::Collection.new.tap do |variables|
       variables.concat(deployment_strategy_default_variables)

spec/models/project_auto_devops_spec.rb

@@ -14,34 +14,6 @@ describe ProjectAutoDevops do
   it { is_expected.to respond_to(:created_at) }
   it { is_expected.to respond_to(:updated_at) }
 
-  describe '#has_domain?' do
-    context 'when domain is defined' do
-      let(:auto_devops) { build_stubbed(:project_auto_devops, project: project, domain: 'domain.com') }
-
-      it { expect(auto_devops).to have_domain }
-    end
-
-    context 'when domain is empty' do
-      let(:auto_devops) { build_stubbed(:project_auto_devops, project: project, domain: '') }
-
-      context 'when there is an instance domain specified' do
-        before do
-          allow(Gitlab::CurrentSettings).to receive(:auto_devops_domain).and_return('example.com')
-        end
-
-        it { expect(auto_devops).to have_domain }
-      end
-
-      context 'when there is no instance domain specified' do
-        before do
-          allow(Gitlab::CurrentSettings).to receive(:auto_devops_domain).and_return(nil)
-        end
-
-        it { expect(auto_devops).not_to have_domain }
-      end
-    end
-  end
-
   describe '#predefined_variables' do
     let(:auto_devops) { build_stubbed(:project_auto_devops, project: project, domain: domain) }