Improve script robustness with set -euo pipefail

[rauldsl]

Description

Enable set -euo pipefail in the GPU Operator NVAIE installation script to improve robustness.
This ensures the script:

• Exits immediately on any command failure (-e)
• Detects use of unset variables (-u)
• Fails if any command in a pipeline fails (-o pipefail)

This change reduces the risk of partial or inconsistent deployments during installation.

Checklist

• No secrets, sensitive information, or unrelated changes
• Lint checks passing (make lint)
• Generated assets in-sync (make validate-generated-assets)
• Go mod artifacts in-sync (make validate-modules)
• Test cases are added for new code paths

Testing

Tested manually by running the script on a cluster with an existing GPU Operator namespace, verifying that:

• The script exits immediately if a required environment variable is missing
• The script stops if any kubectl or helm command fails
• Existing resources are handled correctly without partial creation

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.