XWIKI-9606: Scaled image attachments don't appear in the PDF export
* Don't concatenate the query string to the URL, use the URL factory instead because the URL factory used when exporting to PDF builds a map of (URL, AttachmentReference) which is used later by FOP to resolve URIs and if we modify the URL after it is build by the URL factory the FOP resolve won't be able to find the attachment.

(cherry picked from commit 264b891a5ad5df87365e36b88205c6a7f29915eb)