StreamingService: Wind down resources immediately after streaming.

Wind down resources immediately after streaming. A handler was set up initially
to allow the stream to come back up after a short period and to keep the
notification up for that short period but with the newer code that's
unnecessary.
StreamingService: Don't actually stop mediaPlayer in stopStreaming().

Don't actually stop mediaPlayer in stopStreaming, it's done in
windDownResources() which is called right afterwards.