XWIKI-10225: Can not find attachments with numbers as name
* Improve the way attachment file names are indexed.

(cherry picked from commit 52dafca24061a87cb8b4cd6bffb8c3868c251213)

Conflicts:
	xwiki-platform-core/xwiki-platform-search/xwiki-platform-search-solr/xwiki-platform-search-solr-api/src/main/resources/solr/conf/schema.xml