Remove unused variable $info in DiffusionCloneController.php

Summary:
Left-over from rPa6b550ba0394284441ee55d11e276a05eb568ad9

Closes T15655

Test Plan: Carefully read the source code file to look out for another appearance; after hours of fruitless searching get slightly disappointed.

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15655

Differential Revision: https://we.phorge.it/D25451