Remove orgrepos GraphQL resolvers

Created by: mrnugget

We talked about this in Slack: https://sourcegraph.slack.com/archives/C07KZF47K/p1660744067791599

The code was part of the previous Cloud feature on Sourcegraph.com which doesn't exist anymore, so it's safe to remove.

Of course this doesn't remove everything, but only a single GraphQL query and a mutation. But it makes refactoring the repositories GraphQL layer easier, so I'm going to go ahead and remove it.

Test plan

• Existing tests