chore: remove legacy rnpm config

[szymonrybczak]

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

This Pull Request removes legacy rnpm config. rnpm was depracated ~8 years ago, and currently there's no tool that read this property.

💡 Motivation and Context

Make things simpler.

💚 How did you test it?

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled
• All tests passing
• No breaking changes

🔮 Next steps

[krystofwoldrich]

Thanks, totally make sense.

For context these are the docs of rnpm deprecation and removal in RN Cli v4. https://github.com/react-native-community/cli/blob/8ba278e2ca4c29ee209493bb85a10df5e36b66bb/docs/configuration.md#migration-guide

This config was replaced by https://github.com/getsentry/sentry-react-native/blob/3e864f9297b0aeb2c939615eb2f96ac4c42f1c35/react-native.config.js