cumin2001.codfw.wmnet will replace sarin.codfw.wmnet. Please

• enable it in the ACls which grant access to the management interfaces (which was added in T199074)
• Allow access to the WMCS subnets (currently Cumin on cumin2001 fails to connect to cloudnet1003/1004, labnet1001/1002, labnodepool1001, labvirt* and cloudvirt*

Removing sarin is for later, we'll keep it for a few more weeks as the switchover back to eqiad will still be done with the jessie-based hosts (the new hosts are using Stretch).