Fix LFS false positive spec

ee/app/uploaders/object_storage.rb

@@ -88,7 +88,13 @@ module ObjectStorage
     def changed_mounts
       self.class.uploaders.select do |mount, uploader_class|
         mounted_as = uploader_class.serialization_column(self.class, mount)
-        mount if send(:"#{mounted_as}_changed?") && send(:"#{mounted_as}")&.exists? # rubocop:disable GitlabSecurity/PublicSend
+        uploader = send(:"#{mounted_as}") # rubocop:disable GitlabSecurity/PublicSend
+
+        next unless uploader
+        next unless uploader.exists?
+        next unless send(:"#{mounted_as}_changed?") # rubocop:disable GitlabSecurity/PublicSend
+
+        mount
       end.keys
     end
 

spec/requests/lfs_http_spec.rb

@@ -1025,7 +1025,7 @@ describe 'Git LFS API and storage' do
 
           context 'and workhorse requests upload finalize for a new lfs object' do
             before do
-              allow_any_instance_of(LfsObjectUploader).to receive(:exists?) { false }
+              lfs_object.destroy
             end
 
             context 'with object storage disabled' do