systemd: Fix host name tooltip
systemd: Fix host name tooltip

Use the bootstrap tooltips instead of the in-browser titles, to match
the other tooltips in Cockpit.

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