cdk synth --no-staging seems to produce the same output as cdk synth --staging

### Describe the issue

The [documentation](https://docs.aws.amazon.com/cdk/v2/guide/cli.html#cli-ref) for `cdk synth --staging` says:

> Copy assets to the output directory (use --no-staging to disable, needed for local debugging the source files with SAM CLI)

I tried deleting the cloud assembly and synthesizing using both methods. The resulting file structure in the `cdk.out/` directory was exactly the same. I didn't see a change in how CDK Toolkit creates assets in the cloud assembly. Also, using `cdk synth` (i.e. `--staging`) with SAM CLI worked.

Is the `--no-staging` option still active/needed?

### Links

https://docs.aws.amazon.com/cdk/v2/guide/cli.html#cli-ref
https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-cdk-getting-started.html#serverless-cdk-tutorial-hello-world