DOCSP-14227 -- update OM backup flow diagram-v8.0-backport (791) (#792)

# Backport

This will backport the following commits from `master` to `v8.0`:
- [DOCSP-14227 -- update OM backup flow diagram
(#791)](10gen/docs-ops-manager#791)

<!--- Backport version: 9.6.1 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

Author: jvincent-mongodb