Speed-up buildkite/docker/build.sh
Speed-up buildkite/docker/build.sh

Change-Id: I963199a138def6d6a1b4d437b51d8080831dd797

bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration