test: Fix failures for unexpected virt-host-validate qemu

[martinpitt]

For a few months now, the RHEL downstream gating tests for cockpit-machines have all failed like this:

  File "/source/test/machineslib.py", line 38, in waitPageInit
    virtualization_enabled = "PASS" in self.machine.execute("virt-host-validate qemu | grep 'Checking for hardware virtualization'")
subprocess.CalledProcessError

The actual output shows

QEMU: Checking if device '/dev/kvm' exists: FAIL

and no "hardware virtualization" at all, which makes the grep fail. Treat an absent line as "fail".

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This has repeatedly failed the RHEL 9 gating tests, let's finally fix this.

[packit-as-a-service]

We were not able to find or create Copr project packit/cockpit-project-cockpit-machines-1759 specified in the config with the following error:

Cannot create a new Copr project (owner=packit project=cockpit-project-cockpit-machines-1759 chroots=['fedora-40-x86_64', 'fedora-rawhide-x86_64', 'fedora-39-x86_64']): Copr: 'packit/cockpit-project-cockpit-machines-1759' already exists. Copr HTTP response is 400 BAD REQUEST.

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Unless the HTTP status code above is >= 500, please check your configuration for:

1. typos in owner and project name (groups need to be prefixed with @)
2. whether the project name doesn't contain not allowed characters (only letters, digits, underscores, dashes and dots must be used)
3. whether the project itself exists (Packit creates projects only in its own namespace)
4. whether Packit is allowed to build in your Copr project
5. whether your Copr project/group is not private

[martinpitt]

I'll try a new PR, this COPR failure is annoying.

[martinpitt]

→ #1760