update rgexp hostname for collectd
update rgexp hostname for collectd

Since collectd is now collectd-5.5.2-1.el7.x86_64 on RHEL 7, we noticed that hostname was not well retieved

Change-Id: I1725bfbdee581b7dde5f31e8b9fb63b7af6057d3

redhat-cip/rcip-openshift-ansible,redhat-cip/rcip-openshift-ansible