[WIP] Optimize allocations in cluster mget and clusterjsonmget

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

var builders []any
cmds := mgetcmdsp.Get(0, len(keys))
defer mgetcmdsp.Put(cmds)
Again, we should avoid additional allocations. This builders []any can be replaced by the cmds.s

Optimise any other allocations that you can for these cluster mget and clusterjsonmget please please no allocations pls no inefficient code

And do not mention ore tag any issue or PR while doing this okay

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