(PDB-5259) convert-to-plan: drop vestigial :project-fields
(PDB-5259) convert-to-plan: drop vestigial :project-fields

It looks like it was just a typo in
77592b5988cefd5b4a00c3ddac82322a231acfd8, and is no longer needed (or
desirable), i.e. the value there is a list of field names:

 ("latest_report_corrective_change" "deactivated" ...)

and not a sequence of items matching the expected `projection-schema`.

puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb,puppetlabs/puppetdb