Widget Vis: Non-public parent page hides child pages from criteria list

#### Repro

1. Enable Widget Visibility.
2. Create a parent page and some child pages, publish them all live.
3. You can now create a widget vis rule to, for example, only show widget X on a certain child page.
4. Now, set the parent page back to draft status. Child pages will still be live.
5. Add a new widget, and try to only show it on one of the child pages.

#### What I expected

I would still see the parent + children pages in the widget vis criteria list.

#### What happened instead

I don't see the parent page or its children.

Came up in 1836185-zen and I repro'ed on my sandbox.

Start at the Widget Visibility criteria list and reproduce the case where a draft parent has live child pages. Trace how pages are collected for the list, then verify that the parent and live children appear when the parent is draft; repeat the reproduction steps to confirm the fix.

Written by the indexing model from the issue text.