Nightlies need to build and test (against mock) on more platforms

I initially just created.an integration test pipeline – as the scripted build pipeline was difficult to fix/extend. Now, ideally, we'd build and tests against the mock for many python/platform/architecture combinations first, and then do the integration tests against a much more restricted set. Later, we'd have publishing steps in there as well.

To get part way there, lets do a few things:

• consider mimicking the recent work that was done by Brett with purely scripted pipelines, they render nicely in blue ocean (the future ui for Jenkins)
• add a build and test on many platforms. These can be fixed in code, with the integration set of pythons and server versions as parameters. Check how others are doing it too – best to be similar
• connect the gerrit trigger to this – and only run the build and test when the trigger is used, reserving the integration tests for nightlies and custom runs.
• connect the manual trigger to this as well, changing the params as needed to match.
• perhaps add empty tasks for publishing - and at that point create a ticket for that work. Ideally we'd never release from someone's laptop. There will be issues with this in terms of signing the code, etc... So it should be its own task for later.

Minimum required platforms are: Ubuntu, Centos, Windows and MacOS.