Use the predefined GN override instead.

Also sort the predefined override alphabetically.

Bug: None
Change-Id: I92d0dda5ab416389398d0e88f8b3b9636752486d
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2282277Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>