Fix rendering issue for LDAP configuration provider transactions

Summary: Fixes T4290. At least one of the fields (realname) may have a list of items, and strlen(array('first', 'last')) produces the warning and stack trace in T4290.

Test Plan:

• Edited realname from an array value to an array value.
• Hit error.
• Applied patch.
• No more error.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4290

Differential Revision: https://secure.phabricator.com/D7905