AtomicityHelper: Remove usage of deprecated SubmitInput.waitForMerge

SubmitInput.waitForMerge is deprecated since the merge queue was
removed in I089a5cf49 which was included in Gerrit 2.12.

Remove usage of it, and simplify the call to Submit.apply() by
inlining the input and resource.

Change-Id: I3b55501b764bac24a1aad5ce8ea0c5b87e3d71ad
diff --git a/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java b/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
index 451e770..e9e548d 100644
--- a/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
+++ b/src/main/java/com/criteo/gerrit/plugins/automerge/AtomicityHelper.java
@@ -129,10 +129,8 @@
    * @param info
    */
   public void mergeReview(ChangeInfo info) throws Exception {
-    final SubmitInput input = new SubmitInput();
-    input.waitForMerge = true;
-    final RevisionResource r = getRevisionResource(info.project, info._number);
-    submitter.apply(r, input);
+    submitter.apply(getRevisionResource(info.project, info._number),
+        new SubmitInput());
   }
 
   public RevisionResource getRevisionResource(String project, int changeNumber) throws NoSuchChangeException, OrmException {