When creating AWSMachine instances with throughput specified but iops set to 0 (or omitted), the installer fails with an AWS API error. This occurs because AWS defaults iops to 3000 when not explicitly set, and if the throughput value results in a ratio exceeding AWS's maximum allowed ratio of 0.25 MiBps per iops, the instance creation fails.

Example: If throughput is set to 1200 MiBps and iops is 0 (defaults to 3000), the ratio becomes 1200/3000 = 0.4, which exceeds the maximum allowed ratio of 0.25, causing the following error:

InvalidParameterValue: Throughput (MiBps) to iops ratio of 0.400000 is too high; maximum is 0.250000 MiBps per iops

OpenShift Installer (version with throughput feature for gp3 volumes)

Always reproducible when throughput is specified without a corresponding iops value that satisfies the AWS constraint (throughput / iops <= 0.25)

1. Create an InstallConfig with platform.aws.defaultMachinePlatform.rootVolume.throughput set to a value (e.g., 1200)
2. Do not set iops, or explicitly set iops to 0
3. Run openshift-install create cluster
4. Observe the installation failure during control-plane machine provisioning

Installation fails with error:
- Condition Ready has status: "False", reason: "InstanceProvisionFailed", message: "0 of 3 completed"
- Condition InstanceReady has status: "False", reason: "InstanceProvisionFailed", message: "failed to create AWSMachine instance: failed to run instance: operation error EC2: RunInstances, https response error StatusCode: 400, RequestID: <request-id>, api error InvalidParameterValue: Throughput (MiBps) to iops ratio of 0.400000 is too high; maximum is 0.250000 MiBps per iops"
- Cluster creation fails: "failed to provision control-plane machines within 15m0s"

The installer should either:
1. Automatically calculate and set the minimum required iops based on the throughput value (iops >= throughput / 0.25, rounded up to nearest 100), OR
2. Validate the throughput/iops ratio and provide a clear error message before attempting instance creation, guiding the user to set an appropriate iops value

The installer should prevent this error condition and ensure successful cluster installation.