Unify usage of top level folders short_name

[juliocc]

1. Make short_name optional (use key name/filename if not provided)
2. Disable automation by default
3. Remove enable key from top_level_folders automation field

The idea here is to have make the following work

top_level_folders = {
  test = {
    name       = "test folder"
  }
}

Today this would enable automation, and fail because we're not providing a short name. With this change, the code above works and does not enable automation. IMO this makes more sense since the user is not mentioning automation at all

[ludoo]

very nice, can you also edit the schema?

[ludoo]

I'm also curious about which IAM bindings we're dropping in tests with this PR.

[juliocc]

very nice, can you also edit the schema?

Done. I'm not familiar with the syntax, can you double check it?

I'm also curious about which IAM bindings we're dropping in tests with this PR.

Apparently it's not just some IAM bindings. All the automation resources for the sandbox were missing before. PTAL