GraphQL: Unlock goroutine throttle to match batch capacity (#20146)

We were throttling the amount of concurrent resolvers
at a given time. The idea behind this was to avoid overloading
the database with too many requests.

However, with the introduction of dataloaders, this limitation
actually becomes a bottleneck because all DB calls are actually
batched, so we are unnecessarily throttling the amount of
items that can be processed in a single batch.

The only caveat with this is that now all resolvers
need to backed by dataloaders, or otherwise not be queried
as part of a loop.

In a subsequent PR, we will be removing channel stats
from under channel to be a top-level object to be returned
for a given channel.

```release-note
NONE
```

app/plugin_api.go

@@ -244,7 +244,7 @@ func (api *PluginAPI) DeleteUser(userID string) *model.AppError {
 }
 
 func (api *PluginAPI) GetUsers(options *model.UserGetOptions) ([]*model.User, *model.AppError) {
-	return api.app.GetUsers(options)
+	return api.app.GetUsersFromProfiles(options)
 }
 
 func (api *PluginAPI) GetUser(userID string) (*model.User, *model.AppError) {