ref(grpc): migrate server to context scope API

[giortzisg]

Description

This migrates the grpc integration to use the new scopes API.

Issues

Changelog Entry Instructions

To add a custom changelog entry, uncomment the section above. Supports:

• Single entry: just write text
• Multiple entries: use bullet points
• Nested bullets: indent 4+ spaces

For more details: custom changelog entries

Reminders

• Add GH Issue ID & Linear ID
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

---

_{Stack created with GitHub Stacks CLI • Give Feedback 💬}