[bazel] new_element: Add --bazel-only flag.
[bazel] new_element: Add --bazel-only flag.

Bug: skia:10614
Change-Id: Id31da759ed173ea90a89941beec3d04984ff2da8
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/378576
Commit-Queue: Leandro Lovisolo <f558143c2568be8d55575d13f30a1fc5cb8009d5@google.com>
Reviewed-by: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot