Fix risk area handling to prevent unwanted rate errors and ensure valid methods are still displayed

[robsoned]

Description:

This PR updates the logic responsible for handling delivery methods that contain a delivery_note related to risk areas.

Previously, the module appended an error to the shipping rate result (via append($error) or setError(true)), which prevents Magento from displaying any valid shipping methods, even when they exist. This happened regardless of whether delivery_risk_areas was enabled or disabled, resulting in checkout being blocked unnecessarily.

The new implementation ensures that:

• No error is created when delivery_risk_areas is disabled.
• Only the delivery method containing a risk-related delivery_note is skipped when risk areas are turned off.
• Valid delivery methods continue to be displayed normally.
• Logging occurs only when risk area handling is enabled.
• Error behavior now aligns with configuration expectations.

Checklist:

• Changes are consistent with the project's coding style.
• Link to related issue Shipping methods hidden when delivery_note exists #47

Testing Instructions:

1. With delivery_risk_areas = 0 (disabled):

• Trigger a shipping rate request that includes a delivery_note.
• Confirm no rate error is added.
• Only the method with the delivery_note is skipped.
• All valid shipping methods remain visible.

2. With delivery_risk_areas = 1 (enabled):

• Trigger the same request.
• Confirm the module logs the risk area warning.
• Confirm no rate error is added, and valid methods still display correctly.