OSF: Used model.NewPointer everywhere (#27838)

```release-note
NONE
```

server/config/store.go

@@ -278,7 +278,7 @@ func (s *Store) Load() error {
 	// SetDefaults() will generate missing data. This avoids an additional write
 	// to the backing store.
 	if loadedCfg.ServiceSettings.SiteURL == nil {
-		loadedCfg.ServiceSettings.SiteURL = model.NewString("")
+		loadedCfg.ServiceSettings.SiteURL = model.NewPointer("")
 	}
 
 	// Setting defaults allows us to accept partial config objects.