Node selector doesn't work for node memory hog scenario

[avyas26]

While testing the node memory hog scenario, container always gets created on random node. When verified it is due to the input.yaml template file has selector hard coded as none {}.

https://github.com/redhat-chaos/krkn-hub/blob/main/node-memory-hog/input.yaml.template

Similar file in cpu hog scenario has the variable assigned in the yaml and is working as expected. This has to be updated so to make sure the required node has the memory stress.