(RUF012) Fixed mutable class Defaults- Task 3

[drona-gyawali]

Part of #10196

This PR addresses Part of RUF012 Rule - Task 3, implementing typing.ClassVar across 4 files with a total of 13 changes. The updates primarily focus on enhancing code quality and resolving linting issues (RUF012) related to mutable class attributes.

Technical

• Updated mutable class attributes in 4 files to use typing.ClassVar for clarity and correctness.
• Added ClassVar annotations to mutable class attributes to ensure they are treated as class-level attributes.
• Ensured proper type hints for clarity and type safety.

Testing

Ran ruff check --select RUF012 to confirm no further warnings.

Screenshot

• N/A

Stakeholders

@RayBB

[RayBB]

Looks great to me but I'll need to get a double check from staff :)