fix(config): restore renderer class bases on config update

[emerardd]

Closes #4952.

Summary

• Reapply the renderer through its property setter when updating from another ManimConfig.
• Keep config.renderer synchronized with the class bases managed by ConvertToOpenGL.
• Add a regression test covering an OpenGL tempconfig context, restoration to Cairo, and subsequent Vector construction.

Validation

• 4 focused configuration, metaclass, and ghost-vector tests
• 100 renderer round-trip runtime checks
• Ruff check and formatting
• Targeted mypy check for manim/_config/utils.py
• git diff --check

[behackl]

Ah, that explains the sometimes failing tests due to some sort of renderer corruption -- resetting the renderer was actually broken. Thanks for fixing this, much appreciated! LGTM.