Missing template override control block on kolla-toolbox docker

[Gaël THEROND]

** Bug Report **

What happened:

When building kolla images within an offline environment, we need to completely override the source kolla-toolbox Dockerfile.j2 template in order to make kolla use an internal URL in order to retrieve kolla-toolbox upper-constraints requirements file.

What you expected to happen:

We should be able to override/manipulate the kolla-toolbox upper-constraints URL from the template-override.j2 file and have a successful build.

How to reproduce it:
Try to kolla-build the whole default set of images out of any internet connectivity.
Your build will fail to retrieve the upper-constraints file.

** Environment **:
* OS: CentOS 7 / CentOS 8 Stream
* kernel: 3.10.0-1160.21.1 / 4.18-0.301.1
* Docker image install type: Binary.
* Docker image distribution: CentOS.
* Images from kolla/kolla-ansible pip package distribution.
* Kolla version: 9.3.1 up to master

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/kolla 12.0.1 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/kolla 11.1.0 release.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/kolla 13.0.0.0rc1 release candidate.

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/kolla 10.4.0 release.