issue: [[https://linear.app/comm/issue/ENG-7792/disallow-adding-users-to-community-roots-on-the-keyserver | ENG-7792]]
baseMemberUserSurfacedPermissions is used only in getRolePermissionBlobsForCommunityRoot. userSurfacedPermissions.ADD_MEMBERS permission was parsed by getThreadPermissionBlobFromUserSurfacedPermissions and resulted in two permissions being added to the resultant memberPermissions: add_members and child_open_add_members. We want the permissions for children to stay the same, so we make sure only add_members permission is removed.