Enable probes for dynamic backends
Enable probes for dynamic backends

Make sure probes can be managed outside of the cli thread, now that
backends can be created any time.

gquintard/Varnish-Cache,franciscovg/Varnish-Cache,zhoualbeart/Varnish-Cache,franciscovg/Varnish-Cache,ajasty-cavium/Varnish-Cache,franciscovg/Varnish-Cache,franciscovg/Varnish-Cache,varnish/Varnish-Cache,zhoualbeart/Varnish-Cache,ajasty-cavium/Varnish-Cache,varnish/Varnish-Cache,varnish/Varnish-Cache,franciscovg/Varnish-Cache,gquintard/Varnish-Cache,ajasty-cavium/Varnish-Cache,ajasty-cavium/Varnish-Cache,zhoualbeart/Varnish-Cache,feld/Varnish-Cache,feld/Varnish-Cache,varnish/Varnish-Cache,zhoualbeart/Varnish-Cache,chrismoulton/Varnish-Cache,gquintard/Varnish-Cache,gquintard/Varnish-Cache,ajasty-cavium/Varnish-Cache,feld/Varnish-Cache,feld/Varnish-Cache,chrismoulton/Varnish-Cache,chrismoulton/Varnish-Cache,chrismoulton/Varnish-Cache,varnish/Varnish-Cache,feld/Varnish-Cache,zhoualbeart/Varnish-Cache,chrismoulton/Varnish-Cache