Fix Server Side Ad manager stop

[avelad]

This change causes the safe SS-DAI settings to be reset when a stream is unloaded.

[avelad]

@joeyparrish can you review it?

[joeyparrish]

Were you able to resolve the issue mentioned in the comment?

For SS DAI streams, if a different asset gets unloaded as part of the process of loading a DAI asset, stream manager state gets reset and we don't get any ad events.

Is this not happening any more?

[avelad]

@joeyparrish The problem keeps happening. The problem here is that a part of the code is commented that causes other things to not be released correctly, so I have moved the comment to a lower level (ad_manager vs server_side_ad_manager).

Note: this is a dependency of #3617

[shaka-bot]

All tests passed!

[avelad]

Thanks @joeyparrish !