kubeadm: use UpgradeNodeConfiguration.IgnorePreflightErrors

When using UpgradeNodeConfiguration.IgnorePreflightErrors the field
is currently ignored in favor of the "defualted" field created
by configutil.FetchInitConfigurationFromCluster.

Fix this bug.

Author: neolit123

cmd/kubeadm/app/cmd/upgrade/node.go

@@ -180,11 +180,11 @@ func newNodeData(cmd *cobra.Command, args []string, nodeOptions *nodeOptions, ou
 		return nil, errors.Wrap(err, "unable to fetch the kubeadm-config ConfigMap")
 	}
 
-	ignorePreflightErrorsSet, err := validation.ValidateIgnorePreflightErrors(nodeOptions.ignorePreflightErrors, initCfg.NodeRegistration.IgnorePreflightErrors)
+	ignorePreflightErrorsSet, err := validation.ValidateIgnorePreflightErrors(nodeOptions.ignorePreflightErrors, upgradeCfg.Node.IgnorePreflightErrors)
 	if err != nil {
 		return nil, err
 	}
-	// Also set the union of pre-flight errors to JoinConfiguration, to provide a consistent view of the runtime configuration:
+	// Also set the union of pre-flight errors to InitConfiguration, to provide a consistent view of the runtime configuration:
 	initCfg.NodeRegistration.IgnorePreflightErrors = sets.List(ignorePreflightErrorsSet)
 
 	var patchesDir string