Remove nameservers with any IP in overcloud resolv.conf workaround

Kayobe has a workaround for CentOS cloud images which contain a bogus
nameserver entry in /etc/resolv.conf. By setting
overcloud_host_image_workaround_resolv_enabled to true, the entry would
be removed. Previously we removed a specific IP address - 10.0.2.3 -
that was present in the CentOS 7 images. However, it seems that CentOS 8
images have a different IP - 192.168.122.1.

This change fixes the issue and becomes resilient to future changes by
matching any IP address. This should be fairly safe, since this
workaround is opt-in.

Change-Id: I9323a38cb2bb627ff56f5713900be00595ea8d4b
Story: 2006574
Task: 39484