[Media TTT] Use clientPackageName instead of packageName to fetch

transfer application info.

The client who's notifying SysUI of the transfer needs to create a new
MediaRoute2Info object to inform us about the media route, and they're
only able to access `setClientPackageName`, not `setPackageName`.

Fixes: 241930323
Test: manual
Test: media.taptotransfer tests
Change-Id: Ie17f561d3390ef0daf85a9343f74b3d46355a008