project deletion fails if container registry is setup, but misconfigured
Summary
Encountered in: https://gitlab.zendesk.com/agent/tickets/44594
If the container registry is enabled, but misconfigured (in this example, the registry key file doesn't exist on the filesystem) the project delete service will fail when attempting to remove the project's tags.
Relevant logs and/or screenshots
/data/git/gitlab/log/sidekiq.log:2016-10-17T19:08:29.760Z 23027 TID-owm3j3loc WARN: {"class":"ProjectDestroyWorker","args":[660,3,{}],"retry":true,"queue":"default","jid":"2dcfefad3e4a45cee1108356","created_at":1476729712.7695615,"enqueued_at":1476731309.4037678,"error_message":"Not a directory @ rb_sysopen - config/registry.key","error_class":"Errno::ENOTDIR","failed_at":1476729714.0974588,"retry_count":6,"retried_at":1476731309.760158}