Fix: crmd: Remove unknown nodes with conflicting unames from CIB

When we migrate from corosync-1 plugin to corosync-2 cluster, or from "uname_is_uuid" to "uname_isnt_uuid" cluster, if we are using the existing cib.xml files, that'll result in redundant node entries with conflicting unames. And the nodes will be scheduled to be fenced...

This patch removes unknown nodes with conflicting unames from CIB. This is also part of the fix for "Duplicate nodes appear if IP changes" issue.