Due to poor isolation between the session tests, in particular the
static state in `MediaSession.SESSION_ID_TO_SESSION_MAP`, an unreleased
session at the end of one test can cause subsequent tests to fail with
obscure errors like `Session ID must be unique`.
#minor-release
PiperOrigin-RevId: 600737697
(cherry picked from commit ca61ac6ca35427a697a6645c90cc8e12889c78f7)