virtcontainers: Make max vCPU config less QEMU specific

Even though it's still actually defined as the QEMU upper bound,
it's now abstracted away through govmm.

Signed-off-by: Samuel Ortiz <s.ortiz@apple.com>

src/runtime/virtcontainers/hypervisor_test.go

@@ -185,7 +185,7 @@ func TestHypervisorConfigDefaults(t *testing.T) {
 		MemorySize:        defaultMemSzMiB,
 		DefaultBridges:    defaultBridges,
 		BlockDeviceDriver: defaultBlockDriver,
-		DefaultMaxVCPUs:   defaultMaxQemuVCPUs,
+		DefaultMaxVCPUs:   defaultMaxVCPUs,
 		Msize9p:           defaultMsize9p,
 	}