Added VirtualCapacity to MachineClass NodeTemplate

[elankath]

What this PR does / why we need it:

Which issue(s) this PR fixes: Fixes #

Special notes for your reviewer:

Release note:

Machine Class now has VirtualCapacity that maps to WorkerPool's NodeTemplate VirtualCapacity.

[CLAassistant]

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12 out of 13 committers have signed the CLA.

:white_check_mark: n-boshnakov
:white_check_mark: thiyyakat
:white_check_mark: unmarshall
:white_check_mark: elankath
:white_check_mark: takoverflow
:white_check_mark: acumino
:white_check_mark: aaronfern
:white_check_mark: oliver-goetz
:white_check_mark: ary1992
:white_check_mark: Kumm-Kai
:white_check_mark: timebertt
:white_check_mark: renormalize
:x: Rishabh Patel

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[gardener-robot]

@elankath You need rebase this pull request with latest master branch. Please check.