Adds multiple s390x zones, and rescue for failed VSI creation

[Stringy]

Description

As with GCP, we need to failover to a different zone if VM creation fails. This also handles the clean up of failed VSI creation. The root cause was related to the generation of the ansible inventory - if the creation fails the VSI exists but isn't added to the inventory so subsequent attempts to clean up find nothing to do. Instead, failed VMs are immediately cleaned up

Checklist

• Investigated and inspected CI test results
• Updated documentation accordingly

Automated testing

• Added unit tests
• Added integration tests
• Added regression tests

If any of these don't apply, please comment below.

Testing Performed

CI should be largely sufficient

Manual tests:

• Normal successful run creates the VM and doesn't attempt second creation in the other zone
• Failure after creation attempts to clean up resources
• Failure after first attempt tries to use other zone