Fix crashes in tests due to a reused registry

[devkral]

Checklist

• The code has 100% test coverage.
• The documentation was properly created or updated (if applicable) following the correct guidelines and appropriate language.
• I branched out from the latest main or is a sub-branch.

Summary or description

With edgy 0.25.0 a check was introduced so models don't get automatically replaced when a new model with the same name and
the same registry was specified.
Esmerald uses for tests a central settings object with a cached registry on it. Multiple test files define same named models on the same registry. Guess what? Silent replacements, a source of pain and workarounds and now it finally just crashed on the try.

This PR cleans the silent replacements up. It creates a local Registry for all edgy model defining tests except for cli which uses the edgy_registry now exclusively.