The restart logic is wrong because C* had a bug in
bf599fb5b062cbcc652da78b7d699e7a01b949ad and they fixed later and we
translated the broken version. We must check if there is an existing
endpoint state and call on_restart() hooks on that, not the newly
available endpoint state.
Spotted while inspecting the code.
Acked-by: Asias He <asias@scylladb.com>