cockpit: set log priority to 'info' before looking for entry
    
    We finally saw a test where there were *no* errors logged by the
    time Cockpit reached the log screen, so there were no entries to
    click. Let's just make the test set log level to info before
    looking for entries - I prefer this to 'click entry if found,
    otherwise change log level' as that's twice as many branches to
    look after. Of course, it means the warning triangle entry needle
    is useless now :(
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>