bots: Declare rhel-8-0 image
bots: Declare rhel-8-0 image

We will soon rename our rhel-x image to rhel-8-0.

Closes #10739
deryni/cockpit,martinpitt/cockpit,garrett/cockpit,martinpitt/cockpit,andreasn/cockpit,martinpitt/cockpit,deryni/cockpit,cockpituous/cockpit,garrett/cockpit,mvollmer/cockpit,cockpit-project/cockpit,mvollmer/cockpit,mvollmer/cockpit,deryni/cockpit,mvollmer/cockpit,deryni/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,andreasn/cockpit,mvollmer/cockpit,cockpituous/cockpit,deryni/cockpit,deryni/cockpit,moraleslazaro/cockpit,andreasn/cockpit,moraleslazaro/cockpit,garrett/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,andreasn/cockpit,moraleslazaro/cockpit,garrett/cockpit,martinpitt/cockpit,andreasn/cockpit,cockpit-project/cockpit,deryni/cockpit,cockpituous/cockpit,garrett/cockpit,andreasn/cockpit,andreasn/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpit-project/cockpit