Update Geo replication troubleshooting doc

https://docs.gitlab.com/ee/administration/geo/replication/troubleshooting.html

• There are a number of places where the docs contain instructions based on legacy code and not SSF. All components are now managed by SSF and we should update the content appropriately.

• There a few outdated screen shots which should be updated

• General review to ensure content / links etc are all still valid.