Remove use of ReviewDb to resolve accounts

Starting from Gerrit 2.15 the accounts resolution does not need anymore
a reference to ReviewDb.

Change-Id: I098eb8c5ad8d047630b31537830ad1db29e1e88f
diff --git a/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/worker/UserEventWorker.java b/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/worker/UserEventWorker.java
index af14ed0..126a8b7 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/worker/UserEventWorker.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/rabbitmq/worker/UserEventWorker.java
@@ -115,7 +115,7 @@
                           }
                         });
                 try {
-                  userAccount = accountResolver.find(db, userName);
+                  userAccount = accountResolver.find(userName);
                   if (userAccount == null) {
                     LOGGER.error(
                         "No single user could be found when searching for listenAs: {}", userName);