http2: return this for Http2ServerRequest#setTimeout

Fixes: https://github.com/nodejs/node/issues/33993

PR-URL: https://github.com/nodejs/node/pull/33994


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>