Docker changes to support public vs private builder container build

BUG=None
TEST=CQ

Cq-Depend: chromium:5632314
Cq-Depend: chromium:5634672
Change-Id: I44c15e42a4a7a700aa499ec59d35fab91cc1f5aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/5632274
Tested-by: Varun Srivastav <[email protected]>
Commit-Queue: Varun Srivastav <[email protected]>
Reviewed-by: Azizur Rahman <[email protected]>
(cherry picked from commit d22df985424c84d8e477ed5bd6f5a16c2ab65f71)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/5784774
Tested-by: Derek Beckett <[email protected]>
Commit-Queue: Derek Beckett <[email protected]>
Reviewed-by: Chris DeLaGarza <[email protected]>
15 files changed