refactor(storagecontrol): update `managed_folder_create` sample

[eapl-gemugami]

Description

Based on the RPC Workshop, this sample is updated to the current style guide.

Note: I think that create, get and delete samples should be refactored in the same PR, as they depend on each other for a clean test environment. (After creating a folder it should be deleted, or the strategy in conftest.py should be adapted to these samples)

Checklist

• [x] I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• [x] Tests pass: nox -s py-3.9 (see Test Environment Setup)
• [x] Lint pass: nox -s lint (see Test Environment Setup)
• [ ] Please merge this PR for me once it is approved

[eapl-gemugami]

/gemini review