[Minor] Fix test RetryingBlockFetcherSuite after changed config name

Flakey due to the default retry interval being the same as our test's wait timeout.

Author: Aaron Davidson <aaron@databricks.com>

Closes #3972 from aarondav/fix-test and squashes the following commits:

db77cab [Aaron Davidson] [Minor] Fix test after changed config name

network/shuffle/src/test/java/org/apache/spark/network/shuffle/RetryingBlockFetcherSuite.java

@@ -54,13 +54,13 @@ public class RetryingBlockFetcherSuite {
   @Before
   public void beforeEach() {
     System.setProperty("spark.shuffle.io.maxRetries", "2");
-    System.setProperty("spark.shuffle.io.retryWaitMs", "0");
+    System.setProperty("spark.shuffle.io.retryWait", "0");
   }
 
   @After
   public void afterEach() {
     System.clearProperty("spark.shuffle.io.maxRetries");
-    System.clearProperty("spark.shuffle.io.retryWaitMs");
+    System.clearProperty("spark.shuffle.io.retryWait");
   }
 
   @Test