bots: Clean Fedora mock chroot after building
bots: Clean Fedora mock chroot after building

This frees up ~ 1 GB of wasted space. This should fix tests like
`testContainerProblems` or kubernetes which otherwise run into "low
space" contingency measures like ignoring crashes or removing unused
docker images.

deryni/cockpit,mvollmer/cockpit,SotolitoLabs/cockpit,andreasn/cockpit,garrett/cockpit,martinpitt/cockpit,SotolitoLabs/cockpit,andreasn/cockpit,SotolitoLabs/cockpit,deryni/cockpit,moraleslazaro/cockpit,mareklibra/cockpit,mareklibra/cockpit,SotolitoLabs/cockpit,deryni/cockpit,mareklibra/cockpit,stefwalter/cockpit,cockpit-project/cockpit,mvollmer/cockpit,andreasn/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,deryni/cockpit,mareklibra/cockpit,SotolitoLabs/cockpit,mvollmer/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,garrett/cockpit,cockpit-project/cockpit,garrett/cockpit,andreasn/cockpit,stefwalter/cockpit,stefwalter/cockpit,mareklibra/cockpit,deryni/cockpit,moraleslazaro/cockpit,andreasn/cockpit,deryni/cockpit,deryni/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpituous/cockpit,garrett/cockpit,stefwalter/cockpit,cockpituous/cockpit,cockpituous/cockpit,martinpitt/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,andreasn/cockpit,SotolitoLabs/cockpit,stefwalter/cockpit,mareklibra/cockpit,cockpituous/cockpit,martinpitt/cockpit,garrett/cockpit,cockpituous/cockpit,SotolitoLabs/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,stefwalter/cockpit,andreasn/cockpit,mareklibra/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,stefwalter/cockpit,martinpitt/cockpit