Add EE deprecated value

ee/lib/ee/gitlab/usage_data.rb

@@ -3,6 +3,8 @@
 module EE
   module Gitlab
     module UsageData
+      DEPRECATED_VALUE = -1000
+
       extend ActiveSupport::Concern
 
       EE_MEMOIZED_VALUES = %i(

ee/spec/lib/ee/gitlab/usage_data_spec.rb

@@ -125,7 +125,7 @@ RSpec.describe Gitlab::UsageData do
         network_policy_drops
       ))
 
-      expect(count_data[:projects_with_prometheus_alerts]).to eq(DEPRECATED_VALUE)
+      expect(count_data[:projects_with_prometheus_alerts]).to eq(EE::Gitlab::UsageData::DEPRECATED_VALUE)
       expect(count_data[:feature_flags]).to eq(1)
       expect(count_data[:status_page_projects]).to eq(1)
       expect(count_data[:status_page_issues]).to eq(1)
@@ -268,12 +268,12 @@ RSpec.describe Gitlab::UsageData do
       expect(described_class.usage_activity_by_stage_configure({})).to include(
         projects_slack_notifications_active: 2,
         projects_slack_slash_active: 2,
-        projects_with_prometheus_alerts: DEPRECATED_VALUE
+        projects_with_prometheus_alerts: EE::Gitlab::UsageData::DEPRECATED_VALUE
       )
       expect(described_class.usage_activity_by_stage_configure(described_class.last_28_days_time_period)).to include(
         projects_slack_notifications_active: 1,
         projects_slack_slash_active: 1,
-        projects_with_prometheus_alerts: DEPRECATED_VALUE
+        projects_with_prometheus_alerts: EE::Gitlab::UsageData::DEPRECATED_VALUE
       )
     end
   end