tests: Always prepare bots
tests: Always prepare bots

Image preparing needs bots to be present.
`tools/make-bots` does nothing when `bots/` exists.

Closes #12925
garrett/cockpit,mvollmer/cockpit,deryni/cockpit,cockpit-project/cockpit,martinpitt/cockpit,martinpitt/cockpit,garrett/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpit-project/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,deryni/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,garrett/cockpit,deryni/cockpit,cockpit-project/cockpit,cockpituous/cockpit,deryni/cockpit,mvollmer/cockpit,garrett/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,deryni/cockpit,deryni/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpit-project/cockpit,garrett/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,deryni/cockpit