[WFLY-3866] Fail the :remove-jndi operation if the entry is unknown

JIRA: https://issues.jboss.org/browse/WFLY-3866
Merge pull request #6727 from jmesnil/WFLY-3866_remove-jndi_unknown_entry

[WFLY-3866] Fail the :remove-jndi operation if the entry is unknown
[WFLY-3827] - Update Subsystem for PicketLink Console.