(RUF012) Fixed mutable class Defaults- Task 1 #10278

[ananyakaligal]

Part of #10196

• Prevents accidental modifications of mutable class attributes at the instance level.
• Aligns with project style guidelines enforced by Ruff.

Technical

• Updated mutable class attributes in 3 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.

Stakeholders
@RayBB

[RayBB]

Remove unnecessary navigation changes.
Make sure python tests are passing.
Then you can make this as not draft and tag me.
Thanks!

[ananyakaligal]

yes, working on it