Storages healing mechanism to update default storage

When creating a storage, if the storage has the flag `default=true`, the previous project default storage is synchronously updated to `default=false` (discarding errors if they occur).

We need an async. process that verifies this update has been performed. In cases where it hasn't, it should perform the update.

Start by locating the storage-creation path that handles default=true and the existing process framework for asynchronous work. Trace how the previous project default is updated and how errors are discarded; done means an async process verifies that update and retries it when necessary.

Written by the indexing model from the issue text.