[Kubernetes] Ignore missing pass host header annotation.
[Kubernetes] Ignore missing pass host header annotation.

A missing annotation would previously be handled in the default error
case, causing a noisy warning-level log message to be generated each
time.

We add another case statement to ignore the case where the annotation is
missing from the annotations map.

Also piggybacking a minor improvement to the log message.

SantoDE/traefik,EmileVauge/traefik,thomasbach76/traefik,kekoav/traefik,aantono/traefik,dtomcej/traefik,marco-jantke/traefik,bparli/traefik,martinbaillie/traefik,kekoav/traefik,atbore-phx/traefik,mildis/traefik,vholovko/traefik,jangie/traefik,seryl/traefik,adityacs/traefik,bparli/traefik,ldez/traefik,mihaitodor/traefik,vholovko/traefik,tanyadegurechaff/traefik,marco-jantke/traefik,mihaitodor/traefik,tanyadegurechaff/traefik,thomasbach76/traefik,thomasbach76/traefik,tanyadegurechaff/traefik,mildis/traefik,dtomcej/traefik,mildis/traefik,tanyadegurechaff/traefik,nmengin/traefik,containous/traefik,nmengin/traefik,simbas/traefik,vdemeester/traefik,marco-jantke/traefik,timoreimann/traefik,FriggaHel/traefik,EmileVauge/traefik,ldez/traefik,mihaitodor/traefik,seryl/traefik,containous/traefik,mmatur/traefik,FriggaHel/traefik,timoreimann/traefik,mmatur/traefik,aantono/traefik,martinbaillie/traefik,EmileVauge/traefik,mvdstam/traefik,atbore-phx/traefik,timoreimann/traefik,vdemeester/traefik,aantono/traefik,FriggaHel/traefik,jangie/traefik,mmatur/traefik,timoreimann/traefik,ldez/traefik,kekoav/traefik,simbas/traefik,aantono/traefik,vholovko/traefik,FriggaHel/traefik,nmengin/traefik,bparli/traefik,nmengin/traefik,thomasbach76/traefik,EmileVauge/traefik,containous/traefik,martinbaillie/traefik,aantono/traefik,martinbaillie/traefik,simbas/traefik,kekoav/traefik,marco-jantke/traefik,SantoDE/traefik,seryl/traefik,mmatur/traefik,mvdstam/traefik,containous/traefik,mvdstam/traefik,jangie/traefik,seryl/traefik,mildis/traefik,vdemeester/traefik,atbore-phx/traefik,adityacs/traefik,mvdstam/traefik,dtomcej/traefik,vholovko/traefik,SantoDE/traefik,adityacs/traefik,SantoDE/traefik,mihaitodor/traefik,bparli/traefik,vdemeester/traefik,adityacs/traefik,simbas/traefik,ldez/traefik,jangie/traefik,dtomcej/traefik,atbore-phx/traefik