Fix DetectorSession permissions

onDetected checks permissions for pre-flight instead of data delivery.

Typically this isn't an issue because the AudioRecord will cause timeout
in HDS, but we should be precise.

Also get rid of dead code.

Fixes: 280685301
Test: AlwaysOnHotwordDetectorTest
Test: AGSA with and without mic toggle
Change-Id: I0f6d33f0128771fdc5722f889b8926ee2f1d4693