Remove extraReviewers arg from (Async)ReceiveCommits.Factory

This is never used to pass anything other than an empty multimap,
including internally at Google.

Change-Id: I9ba7fd3a1faf325d5b5b2fa324e7fee68c1ed324

java/com/google/gerrit/sshd/commands/Receive.java

@@ -88,7 +88,7 @@ final class Receive extends AbstractGitCommand {
       throw new Failure(1, "fatal: unable to check permissions " + e);
     }
 
-    AsyncReceiveCommits arc = factory.create(projectState, currentUser, repo, null, reviewers);
+    AsyncReceiveCommits arc = factory.create(projectState, currentUser, repo, null);
 
     try {
       Capable r = arc.canUpload();