🗑️ Deprecation promotion of toPositiveInt extension function to error level

[LVMVRQUXL]

📝 Description

We would like to promote the deprecation of the Number.toPositiveInt() extension function to an error level.

🔗 Dependencies

This issue is blocked by the following ones:

• 🗑️ Deprecation of toPositiveInt extension function with warning level #459

✅ Checklist

• Promote the deprecation of this declaration, remove its tests and update the unreleased changelog.
• Close this issue as completed and update tracking ones if present.

[LVMVRQUXL]

Another implementation of the PositiveInt type will be implemented in #637.