[Backport release-1.4] fix(kubernetes): make node group resources optional when instanceType is set - #3157

…ver instanceType

A node group is sized either by instanceType or by explicit resources, but the
generated values schema required resources on every node group. A node group
with instanceType and no resources — or an empty resources dropped during
typed-CR to HelmRelease translation — failed schema validation with "missing
property 'resources'" even though sizing was fully specified.

Mark resources optional in the node group definition and regenerate the schema,
API types, README, and ApplicationDefinition. The chart template emits
domain.cpu/memory only when resources is present, so a node group sized purely
by instanceType now passes validation and installs.

When a node group sets both instanceType and explicit resources, explicit
resources take precedence: the instancetype is omitted from the rendered VM and
the per-group instancetype lookup is skipped, so KubeVirt accepts the explicit
domain.cpu/memory with no instancetype to conflict with. instanceType stays
required and defaulted (no schema change), so the console's required
instanceType dropdown keeps working — sending the default instanceType plus
explicit resources simply sizes the VM by resources. This replaces an earlier
render-time hard failure on the both-set case, which was unreachable to clear
from the dashboard (the required dropdown cannot be emptied).

Explicit resources are all-or-nothing alongside an instanceType: a partial spec
(only cpu, or only memory) on a group that carries a non-empty instanceType
would emit one domain override next to the instancetype — which KubeVirt rejects
— so it now fails at render time with a clear error. Partial resources on a
group without an instanceType (used to tune kubelet reservations) are unaffected.

Assisted-By: Claude <noreply@anthropic.com>
Signed-off-by: Aleksei Sviridkin <f@lex.la>
(cherry picked from commit a349c75)