Remove unnecessary GerritServer field in Receive command

This is already being setup in the super class, as a protected field
we inherit, thus our field here was shadowing it.

Signed-off-by: Shawn O. Pearce <sop@google.com>

src/main/java/com/google/gerrit/server/ssh/Receive.java

@@ -43,7 +43,6 @@ import com.google.gerrit.client.rpc.Common;
 import com.google.gerrit.git.PatchSetImporter;
 import com.google.gerrit.git.PushQueue;
 import com.google.gerrit.server.ChangeUtil;
-import com.google.gerrit.server.GerritServer;
 import com.google.gerrit.server.mail.CreateChangeSender;
 import com.google.gerrit.server.mail.EmailException;
 import com.google.gerrit.server.mail.MergedSender;
@@ -128,7 +127,6 @@ class Receive extends AbstractGitCommand {
     }
   }
 
-  private GerritServer server;
   private ReceivePack rp;
   private PersonIdent refLogIdent;
   private ReceiveCommand newChange;
@@ -146,12 +144,6 @@ class Receive extends AbstractGitCommand {
 
   private Map<ObjectId, Ref> refsById;
 
-  @Override
-  protected void preRun() throws Failure {
-    super.preRun();
-    server = getGerritServer();
-  }
-
   @Override
   protected void runImpl() throws IOException, Failure {
     if (Common.getGerritConfig().isUseContributorAgreements()