libcore: removed unnecessary code in SSLSocketTest

Was possibly causing a race condition (see b/21776011),
for instance, in case readFirstReceivedChunkFuture
was still executing IoUtils#closeQuietly while the
thread was cancelled.

Bug: 21776011
(cherry picked from commit c22dd77f727262ed8105b8b638aeb817997914fd)

Change-Id: Ibb20a98102d5bdc9ac3eaa0b875801ab218356f1
1 file changed