Two notable changes:
* luci.builder(experiments={...}, ...)
* When realms are enabled, scheduler configs include `realm` field.

R=tandrii@chromium.org
CC=yulanlin@google.com

Change-Id: I17e773bdd33058b71b64c7222f4e8471bf33e83d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2311565Reviewed-by: Andrii Shyshkalov <tandrii@google.com>
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>