Documents with translations are re-indexed on start of XWiki with Oracle database

Steps to reproduce:

Restart XWiki with Oracle as database.

Expected result:

During startup, no pages are re-indexed and thus a log line like INFO o.x.s.s.i.j.IndexerJob - 0 documents added, 0 deleted and 0 updated during the synchronization of the Solr index. is logged shortly after startup.

Actual result:

Some documents are re-indexed, the numbers before added and deleted aren't 0.

This can also be reproduced with the automated test that has been introduced as part of XWIKI-22605. The reason for this is that an empty language is stored as null in the Oracle database and nulls are sorted last while the empty language is sorted first in Solr and other databases.