[BUG] mandatory-services test fails with access error on wavestack, pco1--4

[garloff]

The testcase mandatory-iaas-services.py, included in IaaS v5[.1] scope fails on some clouds.
The error message indicates that the ec2 credential is not valid or fails to access the buckets/containers from swift.

[garloff]

ec2 credentials belong to a user and grant access to the S3 storage belonging to the project it was requested for.
For wavestack and for PCO 1--4, we have EC2 creds that granted S3 access for a different project than the we one we use for testing, causing access failures.
Cleaning up the ec2 creds manually resolved the issue.

[garloff]

We probably should always create a new ec2 credential and clean it up after usage rather than just reusing the old one, which could be stale in case something has changed ...
Let's do this in conjunction with #888

[garloff]

Alternatively, when trying to reuse existing ec2 creds, we could filter for ones that match the correct project.