Minor fix for `CelerityManagementMapWorkflow`
Summary: `phutil_var_export` only accepts a single parameter. This bug was introduced in D9926.
Test Plan: Eye-ball it.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: epriestley, Korvin
Differential Revision: https://secure.phabricator.com/D9930