Move ProjectAlertingSetting and its deps to CE

Moves `ProjectAlertingSetting` and its dependencies from EE to CE.

Contributes to migration of Prometheus alerts to Core

app/models/project.rb

@@ -193,6 +193,7 @@ class Project < ApplicationRecord
   has_one :metrics_setting, inverse_of: :project, class_name: 'ProjectMetricsSetting'
   has_one :grafana_integration, inverse_of: :project
   has_one :project_setting, ->(project) { where_or_create_by(project: project) }, inverse_of: :project
+  has_one :alerting_setting, inverse_of: :project, class_name: 'Alerting::ProjectAlertingSetting'
 
   # Merge Requests for target project should be removed with it
   has_many :merge_requests, foreign_key: 'target_project_id', inverse_of: :target_project
@@ -324,6 +325,7 @@ class Project < ApplicationRecord
   accepts_nested_attributes_for :metrics_setting, update_only: true, allow_destroy: true
   accepts_nested_attributes_for :grafana_integration, update_only: true, allow_destroy: true
   accepts_nested_attributes_for :prometheus_service, update_only: true
+  accepts_nested_attributes_for :alerting_setting, update_only: true
 
   delegate :feature_available?, :builds_enabled?, :wiki_enabled?,
     :merge_requests_enabled?, :forking_enabled?, :issues_enabled?,

ee/app/models/ee/project.rb

@@ -46,7 +46,6 @@ module EE
 
       has_one :service_desk_setting, class_name: 'ServiceDeskSetting'
       has_one :tracing_setting, class_name: 'ProjectTracingSetting'
-      has_one :alerting_setting, inverse_of: :project, class_name: 'Alerting::ProjectAlertingSetting'
       has_one :feature_usage, class_name: 'ProjectFeatureUsage'
       has_one :status_page_setting, inverse_of: :project
 
@@ -182,7 +181,6 @@ module EE
       default_value_for :packages_enabled, true
 
       accepts_nested_attributes_for :tracing_setting, update_only: true, allow_destroy: true
-      accepts_nested_attributes_for :alerting_setting, update_only: true
       accepts_nested_attributes_for :status_page_setting, update_only: true, allow_destroy: true
 
       alias_attribute :fallback_approvals_required, :approvals_before_merge

ee/spec/models/project_spec.rb

@@ -22,7 +22,6 @@ describe Project do
 
     it { is_expected.to have_one(:import_state).class_name('ProjectImportState') }
     it { is_expected.to have_one(:repository_state).class_name('ProjectRepositoryState').inverse_of(:project) }
-    it { is_expected.to have_one(:alerting_setting).class_name('Alerting::ProjectAlertingSetting') }
     it { is_expected.to have_one(:status_page_setting).class_name('StatusPageSetting') }
 
     it { is_expected.to have_many(:reviews).inverse_of(:project) }

spec/models/project_spec.rb

@@ -70,6 +70,7 @@ describe Project do
     it { is_expected.to have_one(:auto_devops).class_name('ProjectAutoDevops') }
     it { is_expected.to have_one(:error_tracking_setting).class_name('ErrorTracking::ProjectErrorTrackingSetting') }
     it { is_expected.to have_one(:project_setting) }
+    it { is_expected.to have_one(:alerting_setting).class_name('Alerting::ProjectAlertingSetting') }
     it { is_expected.to have_many(:commit_statuses) }
     it { is_expected.to have_many(:ci_pipelines) }
     it { is_expected.to have_many(:ci_refs) }