http2: close fd in doSendFileFD()

This commit closes the file descriptor in two code paths that
return from doSendFileFD().

PR-URL: https://github.com/nodejs/node/pull/23047
Fixes: https://github.com/nodejs/node/issues/23029


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>