Steps to reproduce:

1. Open an Item configuration as a user of type "Zabbix Admin".
2. Observe "show value mappings" link is displayed.
3. Click the link.

Result:
A new window is opened with the following message:
Access denied
– You are logged in as "<username>". You have no permissions to access this page.
– If you think this message is wrong, please consult your administrators about getting the necessary permissions.

Expected:
"show value mappings" link is hidden for users with insufficient rights.