speech: API council feedback from model download with a listener

A single listener corresponds to a single model download request
identified by the intent. Hence, instead of setting and clearing
the listener explicitly, the whole pipeline will be covered by
a triggerModelDownload overload.

Bug: 271016482
Test: CTS
Change-Id: I580359009316a325c77e432f74faa7e2431b813a
7 files changed