Using 'property.XWiki.TagClass.tags' in a Solr query returns only case-sensitive matches

You can reproduce by:

• tag an existing page with "TeSt"
• open the main search page
• search for "property.XWiki.TagClass.tags:tEsT"

Expected: the tagged page appears in the search results, because XWIKI-23428 .
Actual: the tagged page doesn't appear in the search results

The reason is because, even if we implemented XWIKI-23428, the query "property.XWiki.TagClass.tags:tEsT" is not expanded to "property.XWiki.TagClass.tags_string_lowercase:tEsT" as can be seen by adding debug=true to the search page URL. The field expansion is controlled by the xwiki.dynamicFieldTypes Solr configuration that is not up-to-date.