remove unused refresher

Originally introduced in
86eb555b8df9ae5e4716d765d9fa4ac83e5b6a6f

References to non_ems_refresher have slowly been removed:
- amazon used as an availability zone
- smart proxy used
- manually added for testing
Merge pull request #1246 from kbrock/unused_refresher

remove unused refresher `NonEmsRefresher`