ice_transport: fix regression on pending when bumping to pj 2.10

With these changes, Jami only got on_data_sent for data that Jami
send. In previous state, some on_data_sent comes from TURN refresh
because it's managed by the ice_session in pjsip.

Change-Id: I76109f9662aeca01ffccd884dac2a5aab7ab2503