Handle SPUBLISH as a non key-based command

[barshaul]

This change ensures that SPUBLISH messages won’t be redirected to a random node if the intended target node isn’t available. The optimization of routing to a random node should only apply to commands that return a MOVED error if the target node isn’t the slot owner. The issue with SPUBLISH is that its behavior is unpredictable when redirected: if the randomly chosen node is outside the slot’s shard, a MOVED error will be returned; otherwise, the command might succeed, leading to inconsistent behavior. To address this, we will implement a PRIMARY_PREFERRED routing strategy for SPUBLISH, deliberately routing failed SPUBLISH commands to other nodes within the same shard.

[ikolomi]

I am not convinced that this policy improves and not degrades the current one:
It is actually better to try publishing on the other nodes in an effort to get the message to through.
The state of publisher does not necessary match the state of the listeners - Hence, under the principle that loosing less connections are more likely than loosing more, having the publisher try to use other connections for completing its job is justified.