Overwite target_project_name for ConfigureRepositoriesStep

As the method 'target_project_name' is based on the
'source_project_name' only for BranchPackageStep and LinkPackageStep but
not for ConfigureRepositories, the method is now re-defined inside
ConfigureRepositoriesStep.

src/api/app/models/workflow/step/configure_repositories.rb

@@ -27,6 +27,10 @@ def project_name
     step_instructions[:project]
   end
 
+  def target_project_name
+    "home:#{@token.user.login}:#{project_name}:PR-#{scm_webhook.payload[:pr_number]}"
+  end
+
   private
 
   def validate_repositories