Add Rake task to update project storage

What does this MR do and why?

Add Rake task to update project storage

With Gitaly no longer allowing storages to share the same path, we may have administrators who need to remove a storage and associate its projects to another.

Add a Rake task to perform this action.

Related to gitlab-com/gl-infra/production#17988 (closed)

MR acceptance checklist

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Choose a project to assign to dummy storage name removed_storage

   project = Project.find_by_full_path('<PROJECT_PATH>')
   project.update_column(:repository_storage, 'removed_storage')

2. Run the rake task to reassign the project back to the default storage

   bundle exec rake "gitlab:gitaly:update_removed_storage_projects[removed_storage, default]"