Move MCM repos to internal concourse

[himanshu-kun]

What would you like to be added:
We would like to move MCM repos external pipelines to internal concourse

Why is this needed:
This will

• helps in dynamic update of infra creadentials for IT
• helps in writing IT for Openstack

[himanshu-kun]

We had a discussion with @ccwienk @AndreasBurger

Short notes

• polling would be required to trigger pipeline on head update or PR creation, as currently we don't have access to external github webhooks from internal github
• arm image build getting stuck can start occuring again on moving to internal as QEMU would be usedThis problem was solved for external concourse by adding ARM nodes, but CCEE doesn't support ARM nodes as of now.
• A proposed approach is to have two pipelines per pipeline we have today. one will be external which will build the images, and post result somewhere, and then other will be internal which will poll for results and will run IT with the resulted images. Although with the current implementation of IT , we don't use these images , but run directly the code.
• We need to research more abt prow before we start working on this, because Prow is external only, but has many features.

cc @rishabh-11 @unmarshall