Design changes for PTL on cpuset mom. (Removal of cpuset skip decorator)

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Most of the tests are being skipped on cpuset mom because of either test is creating vnodes or modifying any of the node attributes.

In intent to run them if possible or skip the test from library itself rather than using a skip decorator these changes are made.

Design changes:

Skip the test on cpuset if the test requests more vnodes than available on a cpuset mom.
Skip the test on cpuset if the test requests more ncpus on a node than available.
Set all node attributes except ncpus and mem if set by qmgr on the available nodes.
If create_vnodes() requests same number of vnodes then return the available vnodes with setting attributes except ncpus and mem.
If create_vnodes() requests less number of vnodes than available then return the requested number of vnodes with setting attributes except ncpus and mem and make the rest of the vnodes offline.
I propose to make mom hostname as default vnode name rather than using vn or vnode. Make changes to all the tests which use any other vnode name.
In a cluster if there is cpuset mom and non cpuset mom and multinode jobs are submitted then skip the test case.

Caveats:

If test requests specific node to run for a job(In a job if mom hostname is requested which will be natural node incase of cpuset and cpus will be 0)- The tests needs to be modified case by case basis.
If test requirement of number of ncpus does not match the available number of ncpus. (In some cases tests might pass and other tests needs skip) – The tests needs to be modified case by case basis.
If vnode name cannot be changed to start with mom hostname then we need to skip testcase. - Need to see case by case basis.