test: Add integration test for cockpit-desktop starting a privileged bridge
test: Add integration test for cockpit-desktop starting a privileged bridge

Reproduces https://bugzilla.redhat.com/show_bug.cgi?id=1820538 and
verifies the fix.

Closes #14324

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