The `DrmConfiguration.sessionForClearTypes` property is often used
to ensure a secure decoder is used for clear ads played in encrypted
content. This is because some devices show black frames when switching
decoders.
Before this change the DRM config isn't propagated down when
constructing the ad media source, meaning
`DrmSessionManager.DRM_UNSUPPORTED` is always used, which will
cause playback to switch from secure to clear decoder when transitioning
to an ad break (ignoring the MediaItem `sessionForClearTypes` option.
Issue: #8568
#minor-release
PiperOrigin-RevId: 356951124
de359cd6fd