Search: Expanded Results needs better fallbacks for "empty-ish" content

I think we should think about better fallbacks for empty content with the expanded results. This is what it looks like when I import a bunch of content:

This is on https://gibrownatomictest.wpcomstaging.com/ where I used the test Woo sample data from https://docs.woocommerce.com/document/importing-woocommerce-sample-data/

Compare this to the minimal view (also not great, but feels less broken):

A site that is full of this is certainly not likely, but it probably is very likely that some content will look like that so I think we need to handle it better. As is, it feels broken. Some ideas:
- I don't think we are showing the categories and tags as fallbacks
- Maybe we can improve indexing: home page should show site title and subtitle. Pull in header image?
- Can we improve the breadcrumbs? The storefront theme actually uses:

Start by reproducing Expanded Results on the staging site with the WooCommerce sample data, then compare it with the minimal view and the Storefront theme breadcrumbs shown in the issue. Define better fallbacks for empty content, including the categories, tags, site title, subtitle, header image, and breadcrumbs described in the report.

Written by the indexing model from the issue text.