Rename pivotaltracker integration

Rename pivotaltracker project association from pivotaltracker_service to
pivotaltracker_integration.

app/models/integration.rb

@@ -48,7 +48,7 @@ class Integration < ApplicationRecord
     flowdock
     hangouts_chat
     irker
-    packagist pipelines_email
+    packagist pipelines_email pivotaltracker
   ].to_set.freeze
 
   def self.renamed?(name)

app/models/project.rb

@@ -180,7 +180,7 @@ class Project < ApplicationRecord
   has_one :mock_ci_service, class_name: 'Integrations::MockCi'
   has_one :packagist_integration, class_name: 'Integrations::Packagist'
   has_one :pipelines_email_integration, class_name: 'Integrations::PipelinesEmail'
-  has_one :pivotaltracker_service, class_name: 'Integrations::Pivotaltracker'
+  has_one :pivotaltracker_integration, class_name: 'Integrations::Pivotaltracker'
   has_one :pushover_service, class_name: 'Integrations::Pushover'
   has_one :redmine_service, class_name: 'Integrations::Redmine'
   has_one :slack_service, class_name: 'Integrations::Slack'

spec/lib/gitlab/import_export/all_models.yml

@@ -372,7 +372,7 @@ project:
 - slack_slash_commands_service
 - irker_integration
 - packagist_integration
-- pivotaltracker_service
+- pivotaltracker_integration
 - prometheus_service
 - flowdock_integration
 - assembla_integration

spec/models/project_spec.rb

@@ -52,7 +52,7 @@ RSpec.describe Project, factory_default: :keep do
     it { is_expected.to have_one(:emails_on_push_integration) }
     it { is_expected.to have_one(:pipelines_email_integration) }
     it { is_expected.to have_one(:irker_integration) }
-    it { is_expected.to have_one(:pivotaltracker_service) }
+    it { is_expected.to have_one(:pivotaltracker_integration) }
     it { is_expected.to have_one(:flowdock_integration) }
     it { is_expected.to have_one(:assembla_integration) }
     it { is_expected.to have_one(:slack_slash_commands_service) }