feature flags: unable to query namespace on sourcegraph.com

Created by: bobheadxi

Querying for the namespace of an override seems to cause auth errors, at least on sourcegraph.com:

API console link

{
  "errors": [
    {
      "message": "org not found: id 2615",
      "path": [
        "featureFlags",
        2,
        "overrides",
        0,
        "namespace"
      ]
    },

Notes from @eseliger https://github.com/sourcegraph/sourcegraph/pull/32237#discussion_r820007660:

Just checked this out in the code, seems like there is some special casing for Sourcegraph.com. I tend to think that that's not the right call though.. 🤔 Everything on the org that is sensitive is guarded by auth checks and that's even documented. I think having orgs accessible in general makes sense though, as they can be owners for various resources. That being said, I don't think we need to change that as part of this PR, but I would actually like to be able to see the namespace here that's why I'm challenging this dotcom check here.