Add fernet keys rotations to our testing.
- Rotate keys every 5 minutes
- Maintain tokens valid 10 minutes
- Keep 4 active keys: (token_expiration / rotation_frequency) +2
10 / 2 + 2 = 4
The frequencies are very short but that way we can have a real scenario
of fernet keys rotations in our CI jobs where Tempest runs during ~15
minutes.
See example on:
https://docs.openstack.org/admin-guide/identity-fernet-token-faq.html
Change-Id: I3d4133ee3a0e3dc52586a6d671d7ef85a9e886d0
Depends-On: I125e81d8cd130fadb8271f1b7bcdcf9794c79f47