Reduce query count on GraphQL user.groups field

Follow up on #26732 (closed)

paginatable_namespace_drop_down_for_project_creation feature flag was disable after finding high DB query counts on production logs.

Might be related to N+1. The problem should be fixed before enabling the feature flag by default.

Query to reproduce the issue (with FF paginatable_namespace_drop_down_for_project_creation enabled)

{
  currentUser {
    groups(permissionScope: CREATE_PROJECTS) {
      nodes {
        fullPath
        path
        name
        webUrl
      }
    }
  }
}