Move UsageStatistics include from EE into FOSS

app/models/event.rb

@@ -7,6 +7,7 @@ class Event < ApplicationRecord
   include DeleteWithLimit
   include CreatedAtFilterable
   include Gitlab::Utils::StrongMemoize
+  include UsageStatistics
 
   default_scope { reorder(nil) }
 

ee/app/models/ee/event.rb

@@ -6,8 +6,6 @@ module EE
     extend ::Gitlab::Utils::Override
 
     prepended do
-      include UsageStatistics
-
       scope :issues, -> { where(target_type: 'Issue') }
       scope :merge_requests, -> { where(target_type: 'MergeRequest') }
       scope :totals_by_author, -> { group(:author_id).count }