Phobos 2.7.0: Sharding can't deliver messages wrapped in ShardingEnvelope when remember-entities is enabled

[Aaronontheweb]

Changes

We're running into an issue with Phobos 2.7.0 under the following conditions:

1. remember-entities is enabled for a given ShardRegion;
2. Phobos tracing is enabled; and
3. The entity actors are being messaged using a ShardingEnvelope

When all three of these conditions are true - the entity actor ends up receiving a ShardingEnvelope instead of the payload inside the ShardingEnvelope, thus the message gets logged as Unhandled.

I believe this is a side-effect of how we're trying to preserve shard tracing, using our SpanEnvelope type internally.

[Aaronontheweb]

Have a reproduction at akkadotnet/akka.net#7452