deps: update llhttp to 5.1.0
cc @nodejs/http @nodejs/http2 Note that handling of h2 preamble has changed and llhttp now returns HPE_PAUSED_H2_UPGRADE error.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
cc @nodejs/http @nodejs/http2 Note that handling of h2 preamble has changed and llhttp now returns HPE_PAUSED_H2_UPGRADE error.