project.config: grant submit access to the 1.21 release branch

Also propagate the LUCI stuff.

Change-Id: I2ef5700a056f968a028018079f02b1bdd3a9076a
Reviewed-on: https://go-review.googlesource.com/c/All-Projects/+/510355
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
2 files changed
tree: 576d031c4569ebd926b232095f22b0d107978e26
  1. buildbucket.config
  2. groups
  3. project.config