Reduce mapreduce shards in tests

This fixes a significant memory consumption issue when running tests.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=129482832

javatests/google/registry/tools/server/ResaveAllEppResourcesActionTest.java

@@ -37,7 +37,7 @@ public class ResaveAllEppResourcesActionTest
   @Before
   public void init() {
     action = new ResaveAllEppResourcesAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>absent(), Optional.<Integer>absent());
+    action.mrRunner = new MapreduceRunner(Optional.<Integer>of(5), Optional.<Integer>absent());
     action.response = new FakeResponse();
   }