Fix output switcher will display previous media session

Before this CL, the same request code will cause intent to
be cached. It will cause the output switcher to display the
previous media session.

This CL uses the package name as an unique request code to
fix this issue.

Bug: 169077753
Test: make -j42 RunSettingsRoboTests
Change-Id: Iebfc7904609e243d5bf0222307bae98a952a3331