Modify release date for 2.18.1 and media3:1.0.0-beta02
Modify release date for 2.18.1 and media3:1.0.0-beta02

Also rearranged release notes to correctly show when the changes were released.

#minor-release

PiperOrigin-RevId: 462361982
(cherry picked from commit c6e69a35a86007762ad0b5e90759b994361d05a1)

google/ExoPlayer,google/ExoPlayer,google/ExoPlayer