rbe_configs_gen produces wrongly formatted Starlark code (flagged by buildifier)

[davido]

I generate RBE config using this command:

  $ ./rbe_configs_gen \
  --bazel_version=4.1.0 \
  --toolchain_container=l.gcr.io/google/rbe-ubuntu18-04:latest \
  --output_src_root=/home/davido/projects/gerrit \
  --output_config_path=tools/rbe \
  --exec_os=linux \
  --target_os=linux

and running the latest buildifier utility on generated code produces this diff: [1].

Used buildifier version:

  $ buildifier -version
buildifier version: 4.0.0 
buildifier scm revision: 840218fa3afc7e7145c1eeb3bfeb612c497e67f7

[1] http://paste.openstack.org/show/805685