Fix bash_it chef recipe: remove history_settings which does not have a template.

@ohrite fixed https://github.com/pivotal/pivotal_workstation/pull/177 bash-it prompt by removing `history_settings.bash` from the templates. Unfortunately, @roderik https://github.com/pivotal/pivotal_workstation/pull/184 added the `history_settings.bash` back to the recipe without its template. This pull-request deletes the reference to `history_settings.bash`.