perf: Pass arguments to RPCs called via GET directly

Previously they were passed as a JSON payload. This results in a LATERAL
join for the calling expression, which prevents LIMIT from being pushed
into the inlined function call, making some requests really slow.

Resolves #2858

CHANGELOG.md

@@ -9,6 +9,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
  - #3558, Add the `admin-server-host` config to set the host for the admin server - @develop7
  - #3607, Log to stderr when the JWT secret is less than 32 characters long - @laurenceisla
+ - #2858, Performance improvements when calling RPCs via GET using indexes in more cases - @wolfgangwalther
 
 ### Fixed