src: node_http2_state.h should not be executable

PR-URL: #17408
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Anatoli Papirovski <[email protected]>
Reviewed-By: Timothy Gu <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Sakthipriyan Vairamani <[email protected]>
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>