Change HttpsURLConnectionTest for okhttp update.

In preparation for an okhttp update. The test broke with the
next okhttp version when tested due to some buffering issue on
devices with long user agent strings: with larger user agents
the headers would be flushed "early" and the client would only
receive the headers and not the body in the single read it
does (which broke the test under CTS). With shorter user agents
(e.g. "Java0" as used under Vogar) it would buffer everything,
send it all and the test would pass.

Rather than fix the webserver in the test it has been removed
and replaced with one based on MockWebServer.

Change-Id: I4ce8558cebb2b87b567c3dbfb75580a575a30946
1 file changed