e2e: KEP-3857: Recursive Read-only (RRO) mounts

Usage:
```
make test-e2e-node \
  TEST_ARGS='--service-feature-gates=RecursiveReadOnlyMounts=true --kubelet-flags="--feature-gates=RecursiveReadOnlyMounts=true"' \
  FOCUS="Mount recursive read-only" SKIP=""
```

Signed-off-by: Akihiro Suda <[email protected]>

Author: AkihiroSuda

test/e2e/nodefeature/nodefeature.go

@@ -91,6 +91,9 @@ var (
 	// TODO: document the feature (owning SIG, when to use this feature for a test)
 	PodResources = framework.WithNodeFeature(framework.ValidNodeFeatures.Add("PodResources"))
 
+	// RecursiveReadOnlyMounts (SIG-node, used for testing recursive read-only mounts <https://kep.k8s.io/3857>)
+	RecursiveReadOnlyMounts = framework.WithNodeFeature(framework.ValidNodeFeatures.Add("RecursiveReadOnlyMounts"))
+
 	// TODO: document the feature (owning SIG, when to use this feature for a test)
 	ResourceMetrics = framework.WithNodeFeature(framework.ValidNodeFeatures.Add("ResourceMetrics"))