Check for remains of DV garbage collection and remove them

[0xFelix]

What happened:

CDI deprecated the DV garbage collection, which was disabled by default for some time now. kubevirt-tekton-tasks should be checked for remains of support for this feature. They can be removed safely now.

See kubevirt/containerized-data-importer#3552

What you expected to happen:
A clear and concise description of what you expected to happen.

How to reproduce it (as minimally and precisely as possible):
Steps to reproduce the behavior.

Additional context:
Add any other context about the problem here.

Environment:

• KubeVirt version (use virtctl version): N/A
• Kubernetes version (use kubectl version): N/A
• VM or VMI specifications: N/A
• Cloud provider or hardware configuration: N/A
• OS (e.g. from /etc/os-release): N/A
• Kernel (e.g. uname -a): N/A
• Install tools: N/A
• Others: N/A

[0xFelix]

/assign @ksimon1