test: Recognize journalctl "-- No entries --" output as harmless
test: Recognize journalctl "-- No entries --" output as harmless

Recent versions of journalctl output this when a query returns no
results.

Fixes #2571
Closes #2582

Reviewed-by: Dominik Perpeet <f7830b2723a5db4fc185058b06cfab4b89a38da9@redhat.com>

garrett/cockpit,Scribery/cockpit,denysvitali/cockpit,mareklibra/cockpit,moolitayer/cockpit,Scribery/cockpit,firebitsbr/cockpit,moolitayer/cockpit,stefwalter/cockpit,xhad/cockpit,haiyangd/cockpit_view,Scribery/cockpit,firebitsbr/cockpit,denysvitali/cockpit,michalskrivanek/cockpit,petervo/cockpit,haiyangd/cockpit_view,cockpituous/cockpit,moraleslazaro/cockpit,Scribery/cockpit,vanloswang/cockpit,matobet/cockpit,cockpit-project/cockpit,SotolitoLabs/cockpit,arilivigni/cockpit,mareklibra/cockpit,SotolitoLabs/cockpit,dperpeet/cockpit,moraleslazaro/cockpit,deryni/cockpit,cockpituous/cockpit,matobet/cockpit,vanloswang/cockpit,deryni/cockpit,xhad/cockpit,xhad/cockpit,SotolitoLabs/cockpit,FireDrunk/cockpit,dperpeet/cockpit,Scribery/cockpit,petervo/cockpit,firebitsbr/cockpit,stefwalter/cockpit,Scribery/cockpit,xhad/cockpit,jscotka/cockpit,cockpituous/cockpit,dperpeet/cockpit,moolitayer/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,petervo/cockpit,sgallagher/cockpit,vanloswang/cockpit,Armstrong1992/cockpit,jscotka/cockpit,moraleslazaro/cockpit,SotolitoLabs/cockpit,garrett/cockpit,michalskrivanek/cockpit,sgallagher/cockpit,stefwalter/cockpit,garrett/cockpit,cockpituous/cockpit,zigitax/cockpit,larskarlitski/cockpit,mareklibra/cockpit,SotolitoLabs/cockpit,mvollmer/cockpit,matobet/cockpit,haiyangd/cockpit_view,arilivigni/cockpit,larsu/cockpit,zigitax/cockpit,andreasn/cockpit,haiyangd/cockpit_view,larsu/cockpit,vanloswang/cockpit,michalskrivanek/cockpit,larskarlitski/cockpit,sgallagher/cockpit,larsu/cockpit,Armstrong1992/cockpit,jscotka/cockpit,firebitsbr/cockpit,michalskrivanek/cockpit,harishanand95/cockpit,harishanand95/cockpit,cockpituous/cockpit,jscotka/cockpit,petervo/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,moolitayer/cockpit,xhad/cockpit,mareklibra/cockpit,sgallagher/cockpit,andreasn/cockpit,martinpitt/cockpit,dperpeet/cockpit,michalskrivanek/cockpit,mvollmer/cockpit,matobet/cockpit,SotolitoLabs/cockpit,Armstrong1992/cockpit,zigitax/cockpit,sgallagher/cockpit,sgallagher/cockpit,larsu/cockpit,FireDrunk/cockpit,andreasn/cockpit,michalskrivanek/cockpit,arilivigni/cockpit,xhad/cockpit,Scribery/cockpit,moolitayer/cockpit,mvollmer/cockpit,Armstrong1992/cockpit,deryni/cockpit,stefwalter/cockpit,zigitax/cockpit,stefwalter/cockpit,sgallagher/cockpit,martinpitt/cockpit,firebitsbr/cockpit,stefwalter/cockpit,mareklibra/cockpit,andreasn/cockpit,FireDrunk/cockpit,denysvitali/cockpit,dperpeet/cockpit,harishanand95/cockpit,vanloswang/cockpit,deryni/cockpit,larskarlitski/cockpit,larsu/cockpit,martinpitt/cockpit,petervo/cockpit,michalskrivanek/cockpit,vanloswang/cockpit,martinpitt/cockpit,haiyangd/cockpit_view,arilivigni/cockpit,larskarlitski/cockpit,jscotka/cockpit,FireDrunk/cockpit,matobet/cockpit,andreasn/cockpit,deryni/cockpit,denysvitali/cockpit,cockpit-project/cockpit,SotolitoLabs/cockpit,moraleslazaro/cockpit,deryni/cockpit,harishanand95/cockpit,mareklibra/cockpit,dperpeet/cockpit,vanloswang/cockpit,larskarlitski/cockpit,xhad/cockpit,dperpeet/cockpit,arilivigni/cockpit,mvollmer/cockpit,FireDrunk/cockpit,harishanand95/cockpit,stefwalter/cockpit,harishanand95/cockpit,denysvitali/cockpit,Armstrong1992/cockpit,larskarlitski/cockpit,jscotka/cockpit,cockpit-project/cockpit,larsu/cockpit,cockpituous/cockpit,arilivigni/cockpit,deryni/cockpit,cockpit-project/cockpit,harishanand95/cockpit,arilivigni/cockpit,andreasn/cockpit,larskarlitski/cockpit,mareklibra/cockpit,zigitax/cockpit,andreasn/cockpit,garrett/cockpit,matobet/cockpit,petervo/cockpit,petervo/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,garrett/cockpit