SDK / exoplayer

The Bluetooth AVRCP service expects the metadata of the item currently
being played to be in sync with the corresponding media description in
the active item of the queue. The comparison expects the metadata values
of `METADATA_KEY_TITLE` and `METADATA_KEY_ARTIST` [1] to be equal to the
`title` and `subtitle` field of the `MediaDescription` [2] of the
corresponding queue item.

Hence we need to populate the media description accordingly to avoid the
BT service to delay the update for two seconds and log an exception.

[1] https://cs.android.com/android/platform/superproject/+/master:packages/modules/Bluetooth/android/app/src/com/android/bluetooth/audio_util/helpers/Metadata.java;l=120
[2] https://cs.android.com/android/platform/superproject/+/master:packages/modules/Bluetooth/android/app/src/com/android/bluetooth/audio_util/MediaPlayerWrapper.java;l=258

Issue: androidx/media#148
PiperOrigin-RevId: 491877806
(cherry picked from commit 2a07a0b4)