Set default values for Blaze ad preview when fetching suggestions fail

[JorgeMucientes]

iOS counterpart: woocommerce/woocommerce-ios#14616

When Blaze API fails to load the suggestion we should avoid showing the ad preview empty and instead set some default values using the selected product data.

• Use product name for ad title
• Use product short description if available or Description for ad description.

The idea is to avoid this empty preview:

[dangermattic]

🚫 Please add a type label (e.g. type: enhancement) and a feature label (e.g. feature: stats) to this issue.