chore: Drop PureAttribute

[Youssef1313]

GitHub Issue (If applicable): closes #

PR Type

What kind of change does this PR introduce?

What is the current behavior?

Pure attribute is used in many places.

What is the new behavior?

As the .NET team decided to drop the attribute for their usages in collections, we can follow them, as the attribute is mostly useless. See dotnet/runtime#35118 (comment)

PR Checklist

Please check if your PR fulfills the following requirements:

• Docs have been added/updated which fit documentation template (for bug fixes / features)
• Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• Validated PR Screenshots Compare Test Run results.
• Contains NO breaking changes
• Associated with an issue (GitHub or internal) and uses the automatic close keywords.
• Commits must be following the Conventional Commits specification.

Other information

Internal Issue (If applicable):

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