Remove digit@chromium.org from OWNERS

According to https://crrev.com/c/5287865/comments/fbd7021f_f74906d2
David is no longer on the Chromium team and so should be removed from
Chromium OWNERS files.

Change-Id: Ibb3d8b6dd7a2fdc128e89ece8b3082d9ae76b1c4
Bug: None
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5296781


Auto-Submit: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1263448}