Empty homepage cached on Solr request timeout

### Problem

Solr requests sometimes time-out while the homepage is rendering. When this happens, an empty homepage is cached and served for at least 5 minutes.

_Homepage view when Solr request times out._

_After refreshing the page._

### Reproducing the bug

This one will be tricky to reproduce. Perhaps the homepage Solr calls could be artificially caused to time-out? I was unable to trigger this error on testing, and was incredibly lucky to have witnessed it on production.

### Context

- Browser (Chrome, Safari, Firefox, etc): Any
- OS (Windows, Mac, etc): Any
- Logged in (Y/N): N
- Environment (prod, dev, local): prod

### Breakdown

#### Requirements Checklist
* [ ]

#### Related files

*

#### Stakeholders

*

#### Instructions for Contributors

- Please [run these commands](https://github.com/internetarchive/openlibrary/wiki/Git-Cheat-Sheet#working-on-your-branch) to ensure your repository is up to date **before** [creating a new branch](https://github.com/internetarchive/openlibrary/wiki/Git-Cheat-Sheet#making-changes-and-creating-a-pull-request) to work on this issue and **each time after** pushing code to Github, because the pre-commit bot may add commits to your PRs upstream.