Support grenade-svm-rolling rename to *-partial-ncpu

I273b82fe2bb449d497f565fe1e2e14e4ea0a59e9 added support for a rolling
upgrade test, we have decided to call it partial-ncpu instead, also
grenade now takes a list of services to hold back
(Ifb733ee2fe0c5bba61b43ae19dca7040c12f7893).

Related devstack-infra/config patch: Ic680502d4dcc0a8677749bc38bf57b6c76c881f7

Change-Id: Icdf43128539e5eee24e47f81b236cede31755a00
Merge "Support grenade-svm-rolling rename to *-partial-ncpu"