fix: prevent infinite loop causing stream freeze in DASH multi-period streams

[totallyunknown]

• Added a condition to ensure requiredIntervalUs > 0 in DashMediaSource.
• Resolves an issue where negative requiredIntervalUs triggered an infinite loop in onPlaylistUpdateRequested(), leading to application/stream freezes.

This fix restores smooth playback for multi-period DASH streams.

This fixes #1698.

[rohitjoins]

Playback freeze persists even after applying this fix. It's unclear if this is directly related to issue #1698.

Assigning it to Toni for a deeper investigation.

[totallyunknown]

@rohitjoins Which stream did you test? I made originally the bisect and my colleague @mikef-dk reported the issue #1698. The test stream we've sent via email didn't freeze anymore. If you have tested with that particular streams it's possible that you've hit an experimental stitchter version on our side.

[rohitjoins]

I tested it with the same stream that was sent via email on a pixel 4A.

[totallyunknown]

I am sorry. I've reverted the version of our service to an older version now. Can you please test again? This stream should not hang with that fix.

[tonihei]

Thanks for the fix proposal, I was able to reproduce the issue and also verify that the fix works. I'll start the merge process and may see further updates (e.g. formatting) appear here.