[Feature Request] Optimise Throttling Allocation Decider

[Bukhtawar]

Is your feature request related to a problem? Please describe

 97.1% (19.4s out of 20s) cpu usage by thread 'opensearch[b869f183befc74cff9f3b5572821ec21][clusterManagerService#updateTask][T#1]'
     2/10 snapshots sharing following 25 elements
       java.base@17.0.9/java.util.Formatter.format(Formatter.java:2625)
       java.base@17.0.9/java.lang.String.format(String.java:4186)
       app//org.opensearch.cluster.routing.allocation.decider.ThrottlingAllocationDecider.allocateNonInitialShardCopies(ThrottlingAllocationDecider.java:250)
       app//org.opensearch.cluster.routing.allocation.decider.ThrottlingAllocationDecider.canAllocate(ThrottlingAllocationDecider.java:200)
       app//org.opensearch.cluster.routing.allocation.decider.AllocationDeciders.canAllocate(AllocationDeciders.java:94)
       app//org.opensearch.cluster.routing.allocation.allocator.LocalShardsBalancer.decideAllocateUnassigned(LocalShardsBalancer.java:927)
       app//org.opensearch.cluster.routing.allocation.allocator.LocalShardsBalancer.allocateUnassigned(LocalShardsBalancer.java:813)
       app//org.opensearch.cluster.routing.allocation.allocator.BalancedShardsAllocator.allocate(BalancedShardsAllocator.java:288)
       app//org.opensearch.cluster.routing.allocation.AllocationService.reroute(AllocationService.java:557)
       app//org.opensearch.cluster.routing.allocation.AllocationService.reroute(AllocationService.java:524)
       app//org.opensearch.node.Node$$Lambda$2608/0x0000008800a32948.apply(Unknown Source)
       app//org.opensearch.cluster.routing.BatchedRerouteService$1.execute(BatchedRerouteService.java:136)
       app//org.opensearch.cluster.ClusterStateUpdateTask.execute(ClusterStateUpdateTask.java:67)
       app//org.opensearch.cluster.service.MasterService.executeTasks(MasterService.java:882)
       app//org.opensearch.cluster.service.MasterService.calculateTaskOutputs(MasterService.java:434)
       app//org.opensearch.cluster.service.MasterService.runTasks(MasterService.java:301)
       app//org.opensearch.cluster.service.MasterService$Batcher.run(MasterService.java:212)
       app//org.opensearch.cluster.service.TaskBatcher.runIfNotProcessed(TaskBatcher.java:209)
       app//org.opensearch.cluster.service.TaskBatcher$BatchedTask.run(TaskBatcher.java:247)
       app//org.opensearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:863)
       app//org.opensearch.common.util.concurrent.PrioritizedOpenSearchThreadPoolExecutor$TieBreakingPrioritizedRunnable.runAndClean(PrioritizedOpenSearchThreadPoolExecutor.java:283)
       app//org.opensearch.common.util.concurrent.PrioritizedOpenSearchThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedOpenSearchThreadPoolExecutor.java:246)
       java.base@17.0.9/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
       java.base@17.0.9/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
       java.base@17.0.9/java.lang.Thread.run(Thread.java:840)
     3/10 snapshots sharing following 23 elements
       app//org.opensearch.cluster.routing.allocation.decider.DiskThresholdDecider.canAllocate(DiskThresholdDecider.java:224)       app//org.opensearch.cluster.routing.allocation.decider.AllocationDeciders.canAllocate(AllocationDeciders.java:94)
       app//org.opensearch.cluster.routing.allocation.allocator.LocalShardsBalancer.decideAllocateUnassigned(LocalShardsBalancer.java:927)
       app//org.opensearch.cluster.routing.allocation.allocator.LocalShardsBalancer.allocateUnassigned(LocalShardsBalancer.java:813)
       app//org.opensearch.cluster.routing.allocation.allocator.BalancedShardsAllocator.allocate(BalancedShardsAllocator.java:288)
       app//org.opensearch.cluster.routing.allocation.AllocationService.reroute(AllocationService.java:557)
       app//org.opensearch.cluster.routing.allocation.AllocationService.reroute(AllocationService.java:524)
       app//org.opensearch.node.Node$$Lambda$2608/0x0000008800a32948.apply(Unknown Source)
       app//org.opensearch.cluster.routing.BatchedRerouteService$1.execute(BatchedRerouteService.java:136)
       app//org.opensearch.cluster.ClusterStateUpdateTask.execute(ClusterStateUpdateTask.java:67)
       app//org.opensearch.cluster.service.MasterService.executeTasks(MasterService.java:882)
       app//org.opensearch.cluster.service.MasterService.calculateTaskOutputs(MasterService.java:434)
       app//org.opensearch.cluster.service.MasterService.runTasks(MasterService.java:301)
       app//org.opensearch.cluster.service.MasterService$Batcher.run(MasterService.java:212)
       app//org.opensearch.cluster.service.TaskBatcher.runIfNotProcessed(TaskBatcher.java:209)
       app//org.opensearch.cluster.service.TaskBatcher$BatchedTask.run(TaskBatcher.java:247)
       app//org.opensearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:863)
       app//org.opensearch.common.util.concurrent.PrioritizedOpenSearchThreadPoolExecutor$TieBreakingPrioritizedRunnable.runAndClean(PrioritizedOpenSearchThreadPoolExecutor.java:283)
       app//org.opensearch.common.util.concurrent.PrioritizedOpenSearchThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedOpenSearchThreadPoolExecutor.java:246)
       java.base@17.0.9/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
       java.base@17.0.9/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
       java.base@17.0.9/java.lang.Thread.run(Thread.java:840)

Describe the solution you'd like

1. Avoid unnecessary String formats
2. Optimise loops by caching static values

Related component

ShardManagement:Performance

Describe alternatives you've considered

No response

Additional context

No response