SECURITY: do not delete avatars uploads when deleting accounts

We rely on the clean up uploads job to do this safely

app/models/user_avatar.rb

@@ -3,8 +3,8 @@ require_dependency 'upload_creator'
 
 class UserAvatar < ActiveRecord::Base
   belongs_to :user
-  belongs_to :gravatar_upload, class_name: 'Upload', dependent: :destroy
-  belongs_to :custom_upload, class_name: 'Upload', dependent: :destroy
+  belongs_to :gravatar_upload, class_name: 'Upload'
+  belongs_to :custom_upload, class_name: 'Upload'
 
   def contains_upload?(id)
     gravatar_upload_id == id || custom_upload_id == id
@@ -46,7 +46,6 @@ class UserAvatar < ActiveRecord::Base
                 user.update!(uploaded_avatar_id: upload.id)
               end
 
-              gravatar_upload&.destroy!
               self.update!(gravatar_upload: upload)
             end
           end

spec/models/user_avatar_spec.rb

@@ -30,6 +30,11 @@ describe UserAvatar do
         expect(avatar.gravatar_upload).to eq(Upload.last)
         expect(avatar.last_gravatar_download_attempt).to eq(Time.now)
         expect(user.reload.uploaded_avatar).to eq(nil)
+
+        expect do
+          avatar.destroy
+        end.to_not change { Upload.count }
+
       end
 
       describe 'when user has an existing custom upload' do
@@ -57,7 +62,8 @@ describe UserAvatar do
 
           avatar.update_gravatar!
 
-          expect(Upload.find_by(id: upload.id)).to eq(nil)
+          # old upload to be cleaned up via clean_up_uploads
+          expect(Upload.find_by(id: upload.id)).not_to eq(nil)
 
           new_upload = Upload.last