Choosing language on PDF Export does not work right after changing the language of the document in view mode

To reproduce:

• Go on a document with translations in multilanguage mode
• Change the language of the document (a language particle should show up in the URL, like language=de)
• go to pdf export
• a dropdown to choose which language of the document should be exported
• if you change the language from the dropdown, the chosen language won't be taken into account, the export will still be done with the langauge chosen at step 2

The issue was introduced by the fix for XWIKI-8253 , in 4.3 milestone 1.