OCPBUGS-81476: Fix race condition in PinnedImages GC test

This commit fixes a race condition in the "All Nodes in a custom Pool
should have the PinnedImages even after Garbage Collection" test that
caused nodes to get stuck in degraded state with missing MachineConfig.

The Problem:
The test was using defers in the wrong order, causing cleanup to happen
like this:
1. Delete KubeletConfig
2. Delete PinnedImageSet (triggers rendered-custom deletion)
3. Unlabel node (triggers transition to worker pool)
4. Wait for worker config

When step 3 triggered the transition, the node would reboot to apply
the worker config. However, because the rendered-custom config was
already deleted in step 2, the node would come back up with a reference
to a non-existent config on disk and get stuck in degraded state:

  currentConfig: rendered-custom-d356ed29481f2de2bb31c6443e1d29ca
  desiredConfig: rendered-worker-82faad7319f9e10715adbfd98a4b67ba
  state: Degraded
  reason: "machineconfig 'rendered-custom-d356ed29481f2de2bb31c6443e1d29ca' not found"

The Fix:
Changed cleanup order to:
1. Unlabel node (triggers transition)
2. Wait for worker config transition to complete
3. Delete KubeletConfig
4. Delete PinnedImageSet

This ensures the node successfully transitions back to the worker pool
BEFORE we delete any configs, eliminating the race condition.

Changes:
- Removed defers for unlabelNode, waitTillNodeReadyWithConfig,
  deletePIS, and deleteKC
- Added explicit cleanup after GCPISTest completes that performs
  operations in the correct order
- Added logging to track cleanup progress
- Removed defer deleteKC from GCPISTest function

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: isabella-janssen

test/extended/machine_config/pinnedimages.go

@@ -94,8 +94,6 @@ var _ = g.Describe("[Suite:openshift/machine-config-operator/disruptive][sig-mco
 		// Add node to custom MCP & wait for the node to be ready in the MCP
 		optedNodes, err := addWorkerNodesToCustomPool(oc, kubeClient, 1, "custom")
 		o.Expect(err).NotTo(o.HaveOccurred(), fmt.Sprintf("Error adding node to `custom` MCP: %v", err))
-		defer waitTillNodeReadyWithConfig(kubeClient, optedNodes[0], workerConfigPrefix)
-		defer unlabelNode(oc, optedNodes[0])
 		framework.Logf("Waiting for `%v` node to be ready in `custom` MCP.", optedNodes[0])
 		waitTillNodeReadyWithConfig(kubeClient, optedNodes[0], customConfigPrefix)
 
@@ -129,12 +127,28 @@ var _ = g.Describe("[Suite:openshift/machine-config-operator/disruptive][sig-mco
 
 		// Apply PIS
 		defer deletePinnedImages(oc, kubeClient, clientSet, optedNodes, pinnedImages, isMetalDisconnected)
-		defer deletePIS(oc, pis.Name)
 		err = applyPIS(oc, pisFixture, pis, pisDiverged)
 		o.Expect(err).NotTo(o.HaveOccurred(), "Applied PIS")
 
 		// Test the images applied in the PIS exist on the node after garbage collection.
 		GCPISTest(oc, kubeClient, clientSet, true, optedNodes[0], kcFixture, gcImage, pis.Name, isMetalDisconnected)
+
+		// Cleanup: Transition node back to worker pool BEFORE deleting configs to avoid race condition.
+		// If we delete the configs while the node is rebooting to transition back to worker pool,
+		// the node may come up with a deleted rendered-custom config and get stuck in degraded state.
+		framework.Logf("Cleaning up: Unlabeling node '%s' to move back to worker pool", optedNodes[0])
+		err = unlabelNode(oc, optedNodes[0])
+		o.Expect(err).NotTo(o.HaveOccurred(), fmt.Sprintf("Error unlabeling node: %v", err))
+
+		framework.Logf("Waiting for node '%s' to transition to worker config", optedNodes[0])
+		waitTillNodeReadyWithConfig(kubeClient, optedNodes[0], workerConfigPrefix)
+
+		// Now it's safe to delete the custom pool configs
+		framework.Logf("Node transitioned successfully, deleting KubeletConfig and PinnedImageSet")
+		err = deleteKC(oc, "custom-gc-config")
+		o.Expect(err).NotTo(o.HaveOccurred(), fmt.Sprintf("Error deleting KubeletConfig: %v", err))
+		err = deletePIS(oc, pis.Name)
+		o.Expect(err).NotTo(o.HaveOccurred(), fmt.Sprintf("Error deleting PinnedImageSet: %v", err))
 	})
 
 	g.It("All Nodes in a Custom Pool should have the PinnedImages in PIS [apigroup:machineconfiguration.openshift.io]", func() {
@@ -384,7 +398,6 @@ func addWorkerNodesToCustomPool(oc *exutil.CLI, kubeClient *kubernetes.Clientset
 // `GCPISTest` completes the body of a PIS test including the garbage collection step
 func GCPISTest(oc *exutil.CLI, kubeClient *kubernetes.Clientset, clientSet *mcClient.Clientset, success bool, nodeName, customGcKCFixture, gcImage, pisName string, isMetalDisconnected bool) {
 	// Apply KC to Pool
-	defer deleteKC(oc, "custom-gc-config")
 	err := oc.Run("apply").Args("-f", customGcKCFixture).Execute()
 	o.Expect(err).NotTo(o.HaveOccurred(), fmt.Sprintf("Error applying garbage collection kubelet config: %s", err))