fix(rlm): remove fcctl-core dependency entirely from Cargo.toml

- Comment out fcctl-core git dependency to prevent CI from trying
  to fetch from private firecracker-rust repository
- Remove unused terraphim_firecracker dependency
- Update firecracker feature to empty list (feature-gated code remains
  in source for manual builds with private repo access)
- Regenerate Cargo.lock to completely remove fcctl-core entries

This fixes the root cause of all CI build failures.

Author: Test User