Previously, a SocketTimeourException is used to signal the end of the stream
that is caused by "no RTP packets received for a while". However, such
signaling is inappropriate under TransferRtpDataChannel, or FakeRtpDataChannel
in RtspPlaybackTests.
Hence, the signaling of end of stream is changed to use RESULT_END_OF_INPUT.
The RtpDataChannel implementations will Still block until a set timeout, but
will return a C.RESULT_END_OF_INPUT should a timeout occur, instead of
throwing a nested SocketTimeoutException.
This also allowed customization of the timeout amount, in
RtspMediaSource.Factory
PiperOrigin-RevId: 380981534
