Revert grep error handling changes - maintain simple implementation

[Copilot]

This PR reverts the proposed grep error handling improvements based on maintainer feedback that the changes increased implementation complexity unnecessarily.

Final Implementation:
The validation maintains the original simple approach:

aks_names=$(grep -oP 'aks_name\s*=\s*"\K[^"]+' "$TERRAFORM_INPUT_FILE" || true)
if [ -z "$aks_names" ]; then
  echo "No aks_name found, skipping validation."
  exit 0
fi

Rationale:
While explicit exit code handling could distinguish between "no matches" and real grep errors, the maintainer determined that the additional complexity was not justified for this use case. The simpler || true pattern is preferred to maintain code readability and maintainability.

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[liyu-ma]

The proposed change increase complexity of the implementation. Decline.

[Copilot]

The proposed change increase complexity of the implementation. Decline.

Understood. Reverted all changes in commit 86258f2, restoring the original simple implementation.