Also remove it from all tests, these aren't covered by the null-checker
Covered by the following package-info.java files:
- j/c/g/a/exoplayer2/ext/mediasession/package-info.java
- j/c/g/a/exoplayer2/package-info.java
- j/c/g/a/exoplayer2/offline/package-info.java
- j/c/g/a/exoplayer2/video/package-info.java
- j/c/g/a/exoplayer2/ui/package-info.java
PiperOrigin-RevId: 277038916
