[MM-28985] Remove pointers to slice (part 1) (#18034)

* Remove pointers to slice (part 1)

* Remove use of pointers to slice from model package (#18045)

* Fix after merge

store/sqlstore/preference_store_test.go

@@ -52,7 +52,7 @@ func TestDeleteUnusedFeatures(t *testing.T) {
 			},
 		}
 
-		err := ss.Preference().Save(&features)
+		err := ss.Preference().Save(features)
 		require.NoError(t, err)
 
 		ss.Preference().(*SqlPreferenceStore).deleteUnusedFeatures()