(RUF012) Fixed mutable class Defaults- Task 2

[ananyakaligal]

Part of #10196
This pull request addresses Part of RUF012 Rule - Task 2, with a focus on enhancing code quality and resolving linting issues related to mutable class attributes.

Technical Details:

• Updated Files: The ClassVar annotations were added to mutable class attributes in two files, ensuring they are treated as class-level attributes. This change resolves the RUF012 linting issues.
• Remaining File: The update could not be applied to plugins/worksearch/schemes/editions.py due to a shared base class with the files mentioned in Task 1, which would introduce an overriding issue. Therefore, the change was not feasible for this file.
• Type Safety: Added proper type hints for better clarity and type safety throughout the affected files.

Testing:
Ran ruff check --select RUF012 to confirm that no further warnings related to mutable class attributes remain.

Screenshot:
N/A
Stakeholders:
@RayBB

[RayBB]

As far as I'm concerned this looks good.
However, I'm going to need to get a second opinion from staff