Limit testing to jenkins containers

[dirgim]

This change limits contra-env-setup CI tests to only build and test for jenkins master and slave containers.

This prevents errors stemming from changes to the contra-env-sample-project (which will have its own CI for testing all the included containers) from blocking the contra-env-setup CI.

Also, now the test_jenkins_running test retries getting the jenkins login page in case the service didn't start up in time for the test run.

[arilivigni]

@dirgim as part of moving the infrastructure out I think the helper containers linchpin and ansible also need to be validated at least for building. Can we also include them as well as the metrics ones as we want to make sure our core infrastructure builds as expected as we discussed a couple of weeks ago.

[dirgim]

@arilivigni I agree, I opened a card to have a separate CI for contra-env-sample-project which would test the building of every container we have there and would trigger on PRs to that repo. My idea is to separate the testing of contra-env-sample-project and testing of contra-env-setup into two distinct CI pipelines.

[arilivigni]

@dirgim sample project would not container infrastructure like Jenkins master/slave, helper containers ansible-executor and linchpin-executor, metrics containers which would be in a new repo called contra-infra. The sample project would contains H-DSL example, Jenkinsfile sample pipelines, and maybe a sample shared library. I updated the document we had a meeting about please take a look and make comments.

[dirgim]

@arilivigni I'll modify this PR so it follows the new structure of the project after we migrate it, but I think the general idea stays the same.

[arilivigni]

@dirgim as long as the helper and metrics containers are included now I am fine with that, but they should be done regardless of the restructure since this is our infra.

[dirgim]

@arilivigni I tested the change, everything looks ok and the test time has been almost halved.

[arilivigni]

LGTM sorry forgot to give final approval