Remove list_directoriers gitaly client method

lib/gitlab/gitaly_client/storage_service.rb

@@ -7,14 +7,6 @@ module Gitlab
         @storage = storage
       end
 
-      # Returns all directories in the git storage directory, lexically ordered
-      def list_directories(depth: 1)
-        request = Gitaly::ListDirectoriesRequest.new(storage_name: @storage, depth: depth)
-
-        GitalyClient.call(@storage, :storage_service, :list_directories, request, timeout: GitalyClient.medium_timeout)
-          .flat_map(&:paths)
-      end
-
       # Delete all repositories in the storage. This is a slow and VERY DESTRUCTIVE operation.
       def delete_all_repositories
         request = Gitaly::DeleteAllRepositoriesRequest.new(storage_name: @storage)