DragonflyDB stream RDB deserialization double-free

Dragonfly is an in-memory data store built for modern application workloads. Prior to 1.40, OpaqueObjLoader::CreateStream in src/server/rdb_load.cc can associate one streamNACK with a consumer group's global PEL and a consumer-local PEL, then free the shared object when a duplicate consumer entry is rejected. Cleanup subsequently frees the same object again. In the default configuration, where Dragonfly ships with authentication disabled, an unauthenticated client can trigger the double-free by sending a crafted serialized stream to RESTORE, causing allocator corruption, denial of service, and potentially attacker-controlled code execution as the Dragonfly service account. The source fix has not yet been mapped to a published release.