[SPARK-11650] Reduce RPC timeouts to speed up slow AkkaUtilsSuite test

This patch reduces some RPC timeouts in order to speed up the slow "AkkaUtilsSuite.remote fetch ssl on - untrusted server", which used to take two minutes to run.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #9869 from JoshRosen/SPARK-11650.

core/src/test/scala/org/apache/spark/util/AkkaUtilsSuite.scala

@@ -340,10 +340,11 @@ class AkkaUtilsSuite extends SparkFunSuite with LocalSparkContext with ResetSyst
       new MapOutputTrackerMasterEndpoint(rpcEnv, masterTracker, conf))
 
     val slaveConf = sparkSSLConfig()
+      .set("spark.rpc.askTimeout", "5s")
+      .set("spark.rpc.lookupTimeout", "5s")
     val securityManagerBad = new SecurityManager(slaveConf)
 
     val slaveRpcEnv = RpcEnv.create("spark-slave", hostname, 0, slaveConf, securityManagerBad)
-    val slaveTracker = new MapOutputTrackerWorker(conf)
     try {
       slaveRpcEnv.setupEndpointRef("spark", rpcEnv.address, MapOutputTracker.ENDPOINT_NAME)
       fail("should receive either ActorNotFound or TimeoutException")