Revert "Adjust to changes in Gerrit core"

Revert submission 283559-currentuser-remove-cache-key

Reason for revert: Causes a latency regression for some hosts
Reverted Changes:
I76bfd3ebc:Adjust to changes in Gerrit core
If7ccfd9a4:Remove unused CurrentUser#cacheKey method
I1378ad083:Remove PerThreadCache

Change-Id: I84965f655d62c258c226ad5d585cee24dea047cc
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 431c7d2..c3556af 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/RemoteSiteUser.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/RemoteSiteUser.java
@@ -28,4 +28,10 @@
   public GroupMembership getEffectiveGroups() {
     return effectiveGroups;
   }
+
+  @Override
+  public Object getCacheKey() {
+    // Never cache a remote user
+    return new Object();
+  }
 }