SDK / exoplayer

https://developers.google.com/search/docs/crawling-indexing/block-indexing#meta-tag

The javadoc will remain hosted on exoplayer.dev, so direct links will
continue to work, but this will remove the pages from search engines
so queries for names like `LoadControl` should be more likely to reach
the current media3 docs instead.

PiperOrigin-RevId: 621838892
(cherry picked from commit da5b9afd68af76cb49fc6daa108ea657d81ecdbb)