[SPARK-12082][FLAKY-TEST] Increase timeouts in NettyBlockTransferSecuritySuite

We should try increasing a timeout in NettyBlockTransferSecuritySuite in order to reduce that suite's flakiness in Jenkins.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #10113 from JoshRosen/SPARK-12082.

core/src/test/scala/org/apache/spark/network/netty/NettyBlockTransferSecuritySuite.scala

@@ -148,7 +148,7 @@ class NettyBlockTransferSecuritySuite extends SparkFunSuite with MockitoSugar wi
         }
       })
 
-    Await.ready(promise.future, FiniteDuration(1000, TimeUnit.MILLISECONDS))
+    Await.ready(promise.future, FiniteDuration(10, TimeUnit.SECONDS))
     promise.future.value.get
   }
 }