Less RoutingNodes allocations (#74911)

No longer create as many RoutingNodes, since they are expensive.

Closes #74325

Author: henningandersen

x-pack/plugin/autoscaling/src/main/java/org/elasticsearch/xpack/autoscaling/storage/ReactiveStorageDeciderService.java

@@ -225,10 +225,9 @@ public static class AllocationState {
         }
 
         public long storagePreventsAllocation() {
-            RoutingNodes routingNodes = new RoutingNodes(state, false);
             RoutingAllocation allocation = new RoutingAllocation(
                 allocationDeciders,
-                routingNodes,
+                state.getRoutingNodes(),
                 state,
                 info,
                 shardSizeInfo,
@@ -242,10 +241,9 @@ public long storagePreventsAllocation() {
         }
 
         public long storagePreventsRemainOrMove() {
-            RoutingNodes routingNodes = new RoutingNodes(state, false);
             RoutingAllocation allocation = new RoutingAllocation(
                 allocationDeciders,
-                routingNodes,
+                state.getRoutingNodes(),
                 state,
                 info,
                 shardSizeInfo,