The cloudscale_floating_ip module failed if no server was assigned to
the floating IP. This also adds a test to avoid a regression.
The only way to have a floating IP without a server assigned is to
delete the server where the floating IP is currently assigned. Under
normal circumstances it's not possible to have an unassigned floating
IP.
* Integration test cleanup for cloudscale modules
This refactors the cleanup procedure for the integration tests of the
cloudscale_server and cloudscale_volume modules to use an "always"
section for cleanup. The cleanup code also deletes all resources which
contain the test run prefix. This ensures that all resources are cleaned
up regardless of the actual test result which is a prerequisite for
running these tests in CI.
* Move cloudscale_floating_ip tests from legacy to integration
This also adds code to make sure that floating IPs are deleted even if a
test run fails. This is unfortunately not possible for floatint IPv6
networks.
