Add redirect for deprecated Blackfire.io content (magento#7054)

* Add redirect for deprecated Blackfire.io content

* Remove unneeded metadata

Author: meker12

src/cloud/project/project-integrate-blackfire.md

@@ -0,0 +1,6 @@
+---
+title: Blackfire.io for Magento Cloud
+redirect_from:
+  - guides/v2.2/cloud/project/project-integrate-blackfire.html
+redirect_to: https://support.blackfire.io/en/articles/771436-step-3-configure-blackfire-to-run-in-all-magento-cloud-environments
+---