Doing so prevent Codec which is a big object with
JNI to be garbage collected.
As the codec can not be hold in the listener, there
is no way to call release, as it must be called on
the same codec.
As a result the release method is also removed.
The downside is that at runtime some callbacks may be
dropped but it should be a short transitive state.
This also simplifies lifecycle of the listener as
the client does not have to know if release needs
to be called or not.
An alternative would have been to hold a weak ref,
but I deemed it too complicated for the
runtime gain.
PiperOrigin-RevId: 290231659
598538253a