res_pjsip_session: Fix multiple leaks.

* Pre-initialize cloned media state vectors to final size to ensure
  vector errors cannot happen later in the clone initialization.
* Release session_media on vector replace failure in
  ast_sip_session_media_state_add.
* Release clone and media_state in ast_sip_session_refresh if we fail to
  append to the stream topology, return an error.

Change-Id: Ib5ffc9b198683fa7e9bf166d74d30c1334c23acb