Figure out how Geo can support existing DR strategy for GitLab.com

We intend to enable Geo on GitLab.com to enhance the existing disaster recovery strategy. To see where Geo can provide value, we need to figure out how each data type is currently backed up and restored.

This issue is still taking shape, but the goal is to understand what exists for disaster recovery on GitLab.com at the moment. So there is a working document to record ideas and notes that can be found here: https://docs.google.com/document/d/1LwLPcSHTCO-Ti6CbX2K92WTWY5hUWeMOA9X1HGp2mFM/edit

We can convert this document to a handbook page when we have better knowledge about what currently exists and where Geo will help.