Correct reference to bulkRoleDrop, refs T835

Test Plan:
- go to settings/users
- click select all
- click role button
- click outside of role dropdown to close it
- see no errors in console

Reviewers: aMoniker, rjmackay

Reviewed By: rjmackay

Subscribers: vladimir, rjmackay

Maniphest Tasks: T835

Differential Revision: https://phabricator.ushahidi.com/D429