Adjust to changes in Gerrit core

Change-Id: I76bfd3ebc04f7f094cefd3c169efbb579ec403ae

src/main/java/com/googlesource/gerrit/plugins/replication/RemoteSiteUser.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/RemoteSiteUser.java b/src/main/java/com/googlesource/gerrit/plugins/replication/RemoteSiteUser.java
index c3556af..431c7d2 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/RemoteSiteUser.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/RemoteSiteUser.java
@@ -28,10 +28,4 @@
   public GroupMembership getEffectiveGroups() {
     return effectiveGroups;
   }
-
-  @Override
-  public Object getCacheKey() {
-    // Never cache a remote user
-    return new Object();
-  }
 }