http2: check if stream is not destroyed before sending trailers

Fixes: https://github.com/nodejs/node/issues/22855
PR-URL: https://github.com/nodejs/node/pull/22896


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>