[2209] Don't release the zone table twice

Removing the release from the test, since the segment now destroys it
itself. We can't check all memory is deallocated at that moment in the
test (since we can't do it before the destroy -- it is not deallocated
fully yet, and can't do it after also, since the memory segment doesn't
exist). But that doesn't matter, since the segment checks by assert.

src/lib/datasrc/tests/memory/zone_writer_unittest.cc

@@ -56,11 +56,6 @@ public:
     void TearDown() {
         // Release the writer
         writer_.reset();
-        // Release the table we used
-        ZoneTable::destroy(segment_->getMemorySegment(),
-                           segment_->getHeader().getTable());
-        // And check we freed all memory
-        EXPECT_TRUE(segment_->getMemorySegment().allMemoryDeallocated());
     }
 protected:
     scoped_ptr<ZoneTableSegment> segment_;