Remove Rinkeby and Kovan infrastructure

[plor]

After the UI has removed support for Rinkeby and Kovan, the services supporting these can be deleted.

• [x] Remove subgraphs for these networks
• [x] Turn off jobs running against DAOs on these networks

[skuhlmann]

@plor

we can't remove the subgraphs, they'll just sit there until thegraph turns them off - but we've removed the configs from our repos.