[Sharding] Duplicate LeastShardAllocationStrategy class

[Arkatufus]

Version Information
Version of Akka.NET?
1.4.31

Which Akka.NET Modules?
Akka.Cluster.Sharding

Describe the bug
There are two classes called LeastShardAllocationStrategy, one in Akka.Cluster.Sharding namespace and another in Akka.Cluster.Sharding.Internal namespace. Will need to determine which one is being used, and if both are being used, need to figure out the repercussion of it.

[ismaelhamed]

They're both used depending on whether you enable the new rebalance algorithm introduced in 1.4.11 or not. For backwards compatibility, the new algorithm is disabled by default, but can be enabled by setting the option least-shard-allocation-strategy.rebalance-absolute-limit > 0

[Aaronontheweb]

Ah, so either we should make that clear inside the comments and / or rename it?

[ismaelhamed]

There's a comment in the old implementation (the one that is used by default for backwards compatibility). I guess this is one of the internal nuances of the project that you must be familiar with.

[Aaronontheweb]

Looking into #6973 and wondering if the old shard allocation strategy might be the culprit here, since that appears to be what's enabled by default and we've never really addressed that.

[Aaronontheweb]

For Akka.NET v1.6, we're going to deprecate the old strategy and move everyone forward onto the new one. We probably should have done this in v1.5 but that we missed that detail.

[Aaronontheweb]

Looking into #6973 and wondering if the old shard allocation strategy might be the culprit here, since that appears to be what's enabled by default and we've never really addressed that.

(I don't think it is, otherwise this would have also been an issue on v1.4 - I suspect it's the changes we made to the shard allocation system in v1.5 that might be responsible, if #6973 is even a real problem at all.)