Don't wrap CANCELLED error in search provider
Don't wrap CANCELLED error in search provider

Our knowledge app search provider was wrapping a
Gio.IOErrorEnum.CANCELLED in our own error type, and handing that to the
shell, which logged it as a failure. Instead, if the operation is
cancelled, then hand a plain old CANCELLED error to the shell.

https://phabricator.endlessm.com/T10595

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib