(3.x.x) Instance Bootstrap Failures and Protected Mode when Launching Large Number of Nodes

## The issue
When launching a large number of instances, bootstrap failures may occur due to a delay in [EC2 API eventual consistency](https://docs.aws.amazon.com/ec2/latest/devguide/eventual-consistency.html).
When this happens, the private IP addresses might not be available in the response of `DescribeInstances` API, even though the ips have been assigned at the response of `RunInstances` API.

This can be seen in the clustermgtd logs:

```
2026-03-04 17:50:20,107 - [slurm_plugin.instance_manager:get_cluster_instances] - WARNING - Ignoring instance i-1234abcd because not all EC2 info are available, exception: KeyError, message: 'PrivateIpAddress'
```

The cluster treats this as a bootstrap failure and can enter protected mode and fail cluster creation. For information on protected mode and how to recover from it, refer to this [documentation](https://docs.aws.amazon.com/parallelcluster/latest/ug/slurm-protected-mode-v3.html).

## Affected ParallelCluster versions, OSes and schedulers
* All ParallelCluster versions and OSes
* Slurm scheduler

## Mitigation

You can find a detailed explanation and the mitigation of the problem [here](https://github.com/aws/aws-parallelcluster/wiki/(3.x.x)-Instance-Bootstrap-Failures-and-Protected-Mode-when-Launching-Large-Number-of-Nodes).