Investigate why Placer has OpenAPI files for download

[JayMurdoch]

Discussed with MW - suggested only Server should have OpenAPI spec. Noted that Placer did not have anything useful as it is a client system (only parameter definitions). To review in future

[dt-r]

This is an IG Publisher feature that autogenerates these files. Raise on zulip if you want to propose not generating these files for clients.