Extensions: fix references being called twice
Created by: chrismwendt
This reverts the changes related to references in PanelView
in the activation PR https://github.com/sourcegraph/sourcegraph/commit/1f5cb556724b167c93a6ae1099633791c44bbc9e#diff-7db962cc6eba00542756a46e8c824e78 and implements the tracking in a way that avoids subscribing to the references results twice.
Helps fix the issue https://github.com/sourcegraph/sourcegraph/issues/2962