bots: Add qemu-block-extra to debian-testing image
bots: Add qemu-block-extra to debian-testing image

Preparation for: https://github.com/cockpit-project/cockpit/pull/11516

Closes: #11997

mvollmer/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,martinpitt/cockpit,garrett/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,deryni/cockpit,cockpituous/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,mvollmer/cockpit,deryni/cockpit,cockpit-project/cockpit,deryni/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpituous/cockpit,deryni/cockpit,deryni/cockpit,cockpit-project/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,deryni/cockpit,martinpitt/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,garrett/cockpit,garrett/cockpit,cockpit-project/cockpit,garrett/cockpit,deryni/cockpit,martinpitt/cockpit,cockpituous/cockpit,cockpit-project/cockpit,garrett/cockpit