[DBSC] Update registration header to the new format

Based on https://github.com/WICG/dbsc/issues/41#issuecomment-2135980399,
update the header to the latest format.

See also https://crrev.com/c/5581762 for the network stack
implementation.

Bug: b/333731555
Change-Id: I085c4db56f64d2ce34f0099cb9062b6a820dcf6c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5614150


Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Alex Ilin <alexilin@chromium.org>
Reviewed-by: Monica Basta <msalama@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1312831}