Access sections can have configs that Gerrit is not aware of. If this
is the case, the AccessSection should not be removed by Gerrit.
One example of a use case is when we roll out new permissions. We then
need to set them before we roll out the permission logic to all our
hosts. We do this by changing the project.config with some non-Gerrit
logic. This is a way of having a permission on a host before the logic
is there and guarantee that there is no interruption for users.
With the current implementation, Gerrit would remove these permissions.
Change-Id: Ie5dadfc64da02d2f4fe75fb750332ddc2890aaa9
93e2a865d7