undo breaking change to kwargs iteration order

This starts to decouple the performance improvement of #24795
from the existence of exactly one implementation of Core.NamedTuple,
in preparation for implementing NamedTuple in Julia rather than C.

src/cluster.jl

@@ -369,7 +369,7 @@ function addprocs(manager::ClusterManager; kwargs...)
 end
 
 function addprocs_locked(manager::ClusterManager; kwargs...)
-    params = merge(default_addprocs_params(), AnyDict(pairs(kwargs)))
+    params = merge(default_addprocs_params(), AnyDict(kwargs))
     topology(Symbol(params[:topology]))
 
     if PGRP.topology != :all_to_all