Uploading bilby results fails as `home.html` is not available

gwcelery.tasks.inference._upload_url fails since home.html is not produced after bilby runs for playground events get completed. A simple workaround for this is just to skip _upload_url for bilby.

@colm.talbot @gregory.ashton Is it the case only when 'FastTest' is turned on? Can we assume that it is produced at ~/public_html/online_pe/{preferred_event_id}/bilby for production runs?