api: configuring fuzzy search min_term_length turns fuzzy search off

### Nomad version

```
Nomad v1.1.0-rc1 (c16a2850549eae74a0bfab5aad359b3c6926280f)
```

### Operating system and Environment details

macOS 10.14.6

```
~/Downloads/nomad-110-rc1 agent -dev -config=server-longer-minimum-search.hcl
```

### Issue

With the following server configuration:

```
server {
search {
min_search_length = 3
}
}
```

Running a fuzzy search query produces the 500 error:

```
curl 'http://localhost:4646/v1/search/fuzzy' --data-raw '{"Text":"xyz","Context":"all"}'

fuzzy search is not enabled
```

#### Expected Result

The [documentation](https://www.nomadproject.io/docs/configuration/search#fuzzy_enabled) says `fuzzy_enabled` defaults to `true` (and that matches with my experience when I don’t specify a server configuration) but setting `min_search_length` appears to override that to `false`.

Start with the /v1/search/fuzzy endpoint and the server.search configuration shown in the report, then reproduce the failure with min_search_length set to 3. Trace how that setting is loaded and how fuzzy search is enabled; done means the documented default remains effective and the curl request no longer returns “fuzzy search is not enabled”.

Written by the indexing model from the issue text.