MM-61229: Place Redis behind enterprise (#28917)

And re-order the server initialization (AGAIN).

For the nth time, we found several bugs in the initialization
process.

1. filestore.NewExportFileBackend and filestore.NewFileBackend
depended on license, but the license wasn't even loaded until
later!
2. The `ps.sqlStore.UpdateLicense` call also didn't work
because the license wouldn't get loaded. It only accidentally
worked because of `ps.AddLicenseListener` which would update
the license later on. We remove that.

Ideally, we would have loaded the license first and then
checked for redis client, but it's very difficult to do that.
Reasons are explained in the code comment.

So we just wait until the license is loaded, and simply throw an
error later.

https://mattermost.atlassian.net/browse/MM-61229
```release-note
NONE
```
---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/api4/apitestlib.go

@@ -112,6 +112,7 @@ func setupTestHelper(dbStore store.Store, searchEngine *searchengine.Broker, ent
 		*memoryConfig.CacheSettings.RedisAddress = redisHost + ":6379"
 		*memoryConfig.CacheSettings.DisableClientCache = true
 		*memoryConfig.CacheSettings.RedisDB = 0
+		options = append(options, app.ForceEnableRedis())
 	}
 	if updateConfig != nil {
 		updateConfig(memoryConfig)