config: fc: Don't expose disable_block_device_use

Relying on virtio-block is the *only* way to use Firecracker with Kata
Containers, as shared FS (virtio-{fs,fs-nydus,9p}) is not supported by
Firecracker.

As configuration doesn't make sense to be exposed, we hardcode the
`false` value in the Firecracker configuration structure.

Fixes: #3813

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

src/runtime/pkg/katautils/config.go

@@ -568,7 +568,7 @@ func newFirecrackerHypervisorConfig(h hypervisor) (vc.HypervisorConfig, error) {
 		EntropySource:         h.GetEntropySource(),
 		EntropySourceList:     h.EntropySourceList,
 		DefaultBridges:        h.defaultBridges(),
-		DisableBlockDeviceUse: h.DisableBlockDeviceUse,
+		DisableBlockDeviceUse: false, // shared fs is not supported in Firecracker,
 		HugePages:             h.HugePages,
 		Debug:                 h.Debug,
 		DisableNestingChecks:  h.DisableNestingChecks,