cardiff: x axis shall use the number of hosts
cardiff: x axis shall use the number of hosts

The plotting was wrong since the X axis was representing the number of
tests and not the number of hosts.

Fixing by enforcing the xtics.

lebauce/edeploy,enovance/edeploy,redhat-cip/edeploy,lebauce/edeploy,enovance/edeploy,redhat-cip/edeploy,redhat-cip/edeploy,redhat-cip/edeploy,enovance/edeploy,enovance/edeploy,lebauce/edeploy,lebauce/edeploy