Reduce mapreduce shards in tests

This fixes a significant memory consumption issue when running tests.

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

javatests/google/registry/billing/ExpandRecurringBillingEventsActionTest.java

@@ -71,7 +71,7 @@ public class ExpandRecurringBillingEventsActionTest
   @Before
   public void init() {
     action = new ExpandRecurringBillingEventsAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>absent(), Optional.<Integer>absent());
+    action.mrRunner = new MapreduceRunner(Optional.<Integer>of(5), Optional.<Integer>absent());
     action.clock = clock;
     action.cursorTimeParam = Optional.absent();
     createTld("tld");

javatests/google/registry/flows/async/DeleteEppResourceActionTestCase.java

@@ -71,7 +71,7 @@ public abstract class DeleteEppResourceActionTestCase<T extends DeleteEppResourc
 
   public void setupDeleteEppResourceAction(T deleteEppResourceAction) throws Exception {
     action = deleteEppResourceAction;
-    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();
     action.clock = clock;
     inject.setStaticField(Ofy.class, "clock", clock);

javatests/google/registry/flows/async/DnsRefreshForHostRenameActionTest.java

@@ -65,7 +65,7 @@ public class DnsRefreshForHostRenameActionTest
   private void runMapreduce(String hostKeyString) throws Exception {
     action = new DnsRefreshForHostRenameAction();
     action.hostKeyString = hostKeyString;
-    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();
     action.run();
     executeTasksUntilEmpty("mapreduce");

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

@@ -74,7 +74,7 @@ public class DeleteProberDataActionTest extends MapreduceTestCase<DeleteProberDa
     persistResource(Registry.get("oa-canary.test").asBuilder().setTldType(TldType.TEST).build());
 
     action = new DeleteProberDataAction();
-    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();
     action.isDryRun = false;
   }

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();
   }