api status page falsely reports Indexer-up status as true when the indexer is running, but not configured correctly

[harywilke]

Context

Zou version: 0.20.76 & 0.20.73
Zou installation type: self-hosted

Describe the bug
The http://localhost/api/status value for "indexer-up" does not accurately show if meilisearch is working with kitsu. It shows true if meilisearch is running, but not false if it is running and misconfigured. I had followed the instructions on seting it up at https://zou.cg-wire.com/ but not https://zou.cg-wire.com/indexer/ which includes adding variables to /etc/zou/zou.env. So my setup was not working, and running zou reset-search-index would throw an IndexerNotInitializedError. But the meilisearch service was running w/o complaints, and a refresh of the /api/status page would produce a meilisearch log entry with a 200 status, and the api/status page would show "indexer-up": "true". I think we need a different test.

Expected behavior
http://localhost/api/status value for "indexer-up" reports true if the indexer is up and running in a working state.

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
This is sort of related to this issue #966 in that we both followed the instructions at https://zou.cg-wire.com/ and missed the environment variables. As the search index is optional, it might be best to eliminate most of the Set up the indexer (optional) section and instead have something like:

Set up the indexer (optional)
To allow full-text search, Kitsu relies on an Indexing engine. It uses the Meilisearch technology.
The indexer is optional. Kitsu can run without it. See Data Indexation

This removes the need to maintain two sets of installation instructions.