The limit was a connection parameter, so it applied to every GIN index
scan, not only full-text search: recipient lookups and Oban job queries
could return incomplete, random results. Set it with SET LOCAL around
the search query only, configurable under Pleroma.Search.DatabaseSearch.
The default stays 500 for search: measured on a 74M-object database,
higher limits or none make searches for common words exceed the query
timeout. Remote fetches for URL queries run outside the transaction.
Based on Akkoma 811f0a468.
Co-authored-by: Oneric <oneric@oneric.stub>