switch radon from public to private IP

it doesn't need a public IP anymore,
sice we put it behind misc. varnish
in I970a5d3e4502, I4ec9d73da766

make it "radon.eqiad.wmnet" instead

Change-Id: Ib02daee91df9bbd254ad84b688623f51da495142
Merge "switch radon from public to private IP"