Adding batching to describe instance API calls

[sarthakkothari]

What type of PR is this?
/kind feature

What this PR does / why we need it:

Node-controller calls DescribeInstances API every time a node joins the cluster. When multiple nodes join the cluster simultaneously, separate EC2 DescribeInstances API calls are made for each node, even though the API supports querying multiple instances in a single call. We are batching the call to EC2 API which reduces the overall call volumes made to EC2 and improve performance.

We have a similar batching for other EC2 calls in Karpenter

Sample Logs

I0520 00:04:26.135372   16837 descibe_instance_batch.go:83] Batched describe instances {
  InstanceIds: [
    "i-038c319c1b9c0c75e",
    "i-02b5e9c459a6cc573",
    "i-04908d55bbfe8be74",
    "i-072a0a9491bacf270"
  ]
}

Reduction in EC2 call volumes with batch -

Without batch -

Improve node controller performance by batching EC2 DescribeInstances API calls.

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Hi @sarthakkothari. Thanks for your PR.

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[k8s-ci-robot]

PR needs rebase.

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