The code was doing `go fakeApp.UpdateProductNotices()`
due to which the Store object was accessed in a racy manner
when it was reset if the localcachelayer flag was set.
We fix this by using the StoreOverride functionality
to pre-define what store to use while initializing the server
itself so that there isn't a need to reset the store _after_
the server is set.
We also apply the same fix in the app and api4 layers too
to prevent similar things from happening there.
https://mattermost.atlassian.net/browse/MM-29487
```release-note
NONE
```
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>