point git://integration.wm.o to zuul.eqiad.wmnet

The internal Jenkins slaves are fetching Zuul references from gallium
using: git://integration.wikimedia.org/

That host is really meant for public consumption and might well be moved
out of gallium in favor of a shared Varnish cache.

The new entry zuul.eqiad.wmnet. points to the server currently hosting
Zuul, aka gallium.wikimedia.org.

DNS entry made by https://gerrit.wikimedia.org/r/#/c/105983/

bug: 59774
Change-Id: I7d65a0882f400d8c316754a8802a264c25f186bf