test: join closing thread

Join the closing thread in the tearDown function in order to make sure
the thread is fully stopped before we return.
This is needed because otherwise we end up with the following error:
java.net.BindException: Address already in use

Signed-off-by: Jean-Louis Dupond <jean-louis@dupond.be>

Author: dupondje

client/src/test/java/org/ovirt/vdsm/jsonrpc/client/reactors/ReactorTestCase.java

@@ -43,9 +43,11 @@ public void setUp() throws Exception {
     }
 
     @After
-    public void tearDown() {
+    public void tearDown() throws InterruptedException {
         this.reactorForListener.close();
         this.reactorForClient.close();
+        this.reactorForListener.join();
+        this.reactorForClient.join();
     }
 
     @Test