Move PrometheusAlert from EE to CE

Moves PrometheusAlert and its dependencies to CE:

* PrometheusAlert class
* Factory
* Associations in: Project, Environment classes

app/models/environment.rb

@@ -11,6 +11,7 @@ class Environment < ApplicationRecord
 
   has_many :deployments, -> { visible }, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
   has_many :successful_deployments, -> { success }, class_name: 'Deployment'
+  has_many :prometheus_alerts, inverse_of: :environment
 
   has_one :last_deployment, -> { success.order('deployments.id DESC') }, class_name: 'Deployment'
   has_one :last_deployable, through: :last_deployment, source: 'deployable', source_type: 'CommitStatus'
@@ -105,6 +106,14 @@ class Environment < ApplicationRecord
     find_or_create_by(name: name)
   end
 
+  def clear_prometheus_reactive_cache!(query_name)
+    cluster_prometheus_adapter&.clear_prometheus_reactive_cache!(query_name, self)
+  end
+
+  def cluster_prometheus_adapter
+    @cluster_prometheus_adapter ||= ::Gitlab::Prometheus::Adapter.new(project, deployment_platform&.cluster).cluster_prometheus_adapter
+  end
+
   def predefined_variables
     Gitlab::Ci::Variables::Collection.new
       .append(key: 'CI_ENVIRONMENT_NAME', value: name)

app/models/project.rb

@@ -244,6 +244,7 @@ class Project < ApplicationRecord
   has_many :management_clusters, class_name: 'Clusters::Cluster', foreign_key: :management_project_id, inverse_of: :management_project
 
   has_many :prometheus_metrics
+  has_many :prometheus_alerts, inverse_of: :project
 
   # Container repositories need to remove data from the container registry,
   # which is not managed by the DB. Hence we're still using dependent: :destroy

ee/app/models/ee/environment.rb

@@ -7,7 +7,6 @@ module EE
     include ::Gitlab::Utils::StrongMemoize
 
     prepended do
-      has_many :prometheus_alerts, inverse_of: :environment
       has_many :self_managed_prometheus_alert_events, inverse_of: :environment
 
       # Returns environments where its latest deployment is to a cluster
@@ -76,14 +75,6 @@ module EE
       end
     end
 
-    def clear_prometheus_reactive_cache!(query_name)
-      cluster_prometheus_adapter&.clear_prometheus_reactive_cache!(query_name, self)
-    end
-
-    def cluster_prometheus_adapter
-      @cluster_prometheus_adapter ||= ::Gitlab::Prometheus::Adapter.new(project, deployment_platform&.cluster).cluster_prometheus_adapter
-    end
-
     def protected?
       project.protected_environment_by_name(name).present?
     end

ee/app/models/ee/project.rb

@@ -83,7 +83,6 @@ module EE
 
       has_many :webide_pipelines, -> { webide_source }, class_name: 'Ci::Pipeline', inverse_of: :project
 
-      has_many :prometheus_alerts, inverse_of: :project
       has_many :prometheus_alert_events, inverse_of: :project
       has_many :self_managed_prometheus_alert_events, inverse_of: :project