Check for new media session token

Fixes: 158288114
Test: manual - Cast from Spotify. Dismiss the app. Cast from Spotify
again and look at the device shown in the QS player. It should not show
"Phone speaker".
Test: atest tests/src/com/android/systemui/media/MediaDeviceManagerTest.kt

Change-Id: I637f304f4b7e35ec7dfa7b0b30593d9fcf50a586