In some cases, the IMA SDK fails to call the expected loadAd
event to load the next ad to play. This is (potentially) the
only remaining case where playback can get stuck due to missing
calls from IMA as the player doesn't even have a MediaSource at
this stage and is only waiting for IMA to provide the ad URL.
We can reuse the existing adPreloadTimeoutMs that was added for
a similar purpose (when preloading the first ad in the group).
The JavaDoc matches this purpose as well and the default timeout
is appropriate since we expect to get the loadAd call immediately.
Issue: google/ExoPlayer#10510
PiperOrigin-RevId: 466953617
b125d45a63