Fix bug in tutorial setup script for replication

Author: ferno-ms

articles/sql-database/replication-with-sql-database-managed-instance.md

@@ -243,8 +243,8 @@ EXEC sp_addpushsubscription_agent
   @subscriber_security_mode = 0,
   @subscriber_login = N'$(target_username)',
   @subscriber_password = N'$(target_password)',
-  @job_login = N'$(target_username)',
-  @job_password = N'$(target_password)';
+  @job_login = N'$(username)',
+  @job_password = N'$(password)';
 
 -- Initialize the snapshot
 EXEC sp_startpublication_snapshot