Prevent `WP_List_Table::search_box()` from throwing an array to string conversion notice when post list tables are loaded with an array of orderby parameters in the URL, eg: `/wp-admin/edit.php?post_type=page&orderby[menu_order]=ASC&orderby[title]=ASC`.
Follow up to [29027].
Props leonidasmilossis, rajinsharwar, swissspidy, NomNom99, pls78, SergeyBiryukov.
Fixes#59494.
See #17065.
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