[Gluster-infra] FYI: resolv.conf needs to be updated on build.gluster.org after reboot

[Kaushal M]

The resolv.conf generated by NetworkManager on build.gluster.org sets
the hypervisor as the nameserver. The hypervisor always returns the
old, local ip for review.gluster.org. Because of this jenkins will not
be able to connect to the migrated gerrit instance.

To fix this, I've modified /etc/resolv.conf to use the google dns
servers, and restarted jenkins.

The exact steps I followed,

1. Added `nameserver=8.8.8.8` as the first nameserver in /etc/resolv.conf
2. Restarted jenkins.

This needs to be done after restart of build.g.o till it is migrated
(so probably wouldn't need to be done ever).

If I find a way to make this stick through reboots, I'll update here.

~kaushal