MINOR: Removed unused WorkflowAction::get_dropdown_map() function.
MINOR: Removed unused WorkflowAction::get_dropdown_map() function.

silverstripe-terraformers/advancedworkflow,dnadesign/advancedworkflow,silverstripe-australia/silverstripe-advancedworkflow,silverstripe-terraformers/advancedworkflow,dnadesign/advancedworkflow,Internetrix/advancedworkflow,silverstripe-australia/advancedworkflow,icecaster/advancedworkflow,silverstripe-australia/advancedworkflow,Internetrix/advancedworkflow,icecaster/advancedworkflow,silverstripe-australia/silverstripe-advancedworkflow