Seastar httpd recommended users to stop using contiguous requet.content string and read body they need from request's input_stream instead. However, "official" deprecation of request content had been only made recently.
This PR patches REST API server to turn this feature on and patches few handlers that mess with request bodies to read them from request stream.
Using newer seastar API, no need to backport
Closesscylladb/scylladb#26418
* github.com:scylladb/scylladb:
api: Switch to request content streaming
api: Fix indentation after previous patch
api: Coroutinize set_relabel_config handler
api: Coroutinize set_error_injection handler
8b0bfb817e