tools: Add Conflicts: to newer firewalld that ships cockpit service
tools: Add Conflicts: to newer firewalld that ships cockpit service

When building cockpit for older Debian/Ubuntu releases that have
firewalld < 0.6, cockpit-ws ships its service file. On these, ensure
that we conflict to newer firewalld versions that start shipping it, to
ensure a correct upgrade order and avoid file conflicts.

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