unit tests: fix breakage caused by client-go & apimachinery bump

Changes in the apimachinery and client-go packages broke our unit
tests after upgrade. client-go stopped serializing the empty
preferences: {} field for the kubeconfig. apimachinery, with
kubernetes/apimachinery@c58e197
caused much more extensive breakage by changing the format with
which errors are returned, and our unit tests hard code the
expected error messages.

For the most part, I used claude to fix these issues, and here
is the summary it created:

Changes Made
Root Cause: The k8s apimachinery package (errors.go:93-96) now uses json.Marshal()
to format BadValue in error messages instead of Go's native format. Error Format Changes:

Arrays: []string{"a", "b"} → ["a","b"] (JSON format, no spaces)
Nil values: []string(nil) → null
Structs: aws.Subnet{ID:"x", Roles:...} → {"id":"x"} (JSON with lowercase keys)
Custom types: gcp.OSImage{Name:"x", Project:"y"} → {"name":"x","project":"y"}

Author: patrickdillon

cmd/node-joiner/testdata/add-nodes-overrides.txt

@@ -31,7 +31,6 @@ status:
 apiVersion: agent-install.openshift.io/v1beta1
 kind: InfraEnv
 metadata:
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/configimage/manifests/default_manifests.txt

@@ -47,7 +47,6 @@ rendezvousIP: 192.168.111.20
 apiVersion: extensions.hive.openshift.io/v1beta1
 kind: AgentClusterInstall
 metadata:
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:
@@ -79,7 +78,6 @@ status:
 apiVersion: hive.openshift.io/v1
 kind: ClusterDeployment
 metadata:
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:
@@ -101,7 +99,6 @@ status: {}
 apiVersion: hive.openshift.io/v1
 kind: ClusterImageSet
 metadata:
-  creationTimestamp: null
   name: openshift-was not built correctly
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/image/assets/with_additional_ntp_sources.txt

@@ -53,7 +53,6 @@ logdir /var/log/chrony
 apiVersion: agent-install.openshift.io/v1beta1
 kind: InfraEnv
 metadata:
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/image/configurations/baremetal_host_bmc_config.txt

@@ -134,7 +134,6 @@ kind: AgentClusterInstall
 metadata:
   annotations:
     agent-install.openshift.io/install-config-overrides: '{"platform":{"baremetal":{"hosts":[{"name":"master-0","bmc":{"username":"foo","password":"pwd1","address":"http://172.22.0.10:8000/redfish/v1/Systems/d3fe1eb9-f04c-465d-b5d6-d267f0a0059b","disableCertificateVerification":false},"role":"","bootMACAddress":"00:00:00:aa:bb:01","hardwareProfile":""},{"name":"master-1","bmc":{"username":"foo","password":"pwd2","address":"http://172.22.0.11:8000/redfish/v1/Systems/65bf6806-b634-4494-bccf-032ebdecc65d","disableCertificateVerification":false},"role":"","bootMACAddress":"00:00:00:aa:bb:02","hardwareProfile":""},{"name":"master-2","bmc":{"username":"foo","password":"pwd3","address":"http://172.22.0.12:8000/redfish/v1/Systems/ff67e706-28c4-42f6-b9a2-ce714195300a","disableCertificateVerification":false},"role":"","bootMACAddress":"00:00:00:aa:bb:03","hardwareProfile":""}],"clusterProvisioningIP":"172.22.0.3","provisioningNetwork":"Managed","provisioningNetworkInterface":"enp1s0","provisioningNetworkCIDR":"172.22.0.0/24","provisioningDHCPRange":"172.22.0.10,172.22.0.254"}}}'
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/image/configurations/control-plane-4-replicas.txt

@@ -60,7 +60,6 @@ DefaultEnvironment=NO_PROXY="172.22.0.0/24,virthost.ostest.test.metalkube.org,19
 apiVersion: extensions.hive.openshift.io/v1beta1
 kind: AgentClusterInstall
 metadata:
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/image/configurations/control-plane-5-replicas.txt

@@ -60,7 +60,6 @@ DefaultEnvironment=NO_PROXY="172.22.0.0/24,virthost.ostest.test.metalkube.org,19
 apiVersion: extensions.hive.openshift.io/v1beta1
 kind: AgentClusterInstall
 metadata:
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/image/configurations/external_compact.txt

@@ -49,7 +49,6 @@ kind: AgentClusterInstall
 metadata:
   annotations:
     agent-install.openshift.io/install-config-overrides: '{"platform":{"external":{"platformName":"some-cloud-provider"}}}'
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/image/configurations/external_with_bootArtifactsBaseURL_minimal_iso.txt

@@ -54,7 +54,6 @@ kind: AgentClusterInstall
 metadata:
   annotations:
     agent-install.openshift.io/install-config-overrides: '{"platform":{"external":{"platformName":"oci","cloudControllerManager":"External"}}}'
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/image/configurations/external_without_bootArtifactsBaseURL_minimal_iso.txt

@@ -52,7 +52,6 @@ kind: AgentClusterInstall
 metadata:
   annotations:
     agent-install.openshift.io/install-config-overrides: '{"platform":{"external":{"platformName":"oci","cloudControllerManager":"External"}}}'
-  creationTimestamp: null
   name: ostest
   namespace: cluster0
 spec:

cmd/openshift-install/testdata/agent/image/configurations/nutanix_compact.txt

@@ -63,7 +63,6 @@ kind: AgentClusterInstall
 metadata:
   annotations:
     agent-install.openshift.io/install-config-overrides: '{"platform":{"nutanix":{"prismCentral":{"endpoint":{"address":"pc1.test.metalkube.org","port":9440},"username":"testUser","password":"testPassword"},"prismElements":[{"uuid":"00061f7f-44f7-19dc-72gc-7cc25586ee53","endpoint":{"address":"pe1.test.metalkube.org","port":9440}}],"apiVIPs":["192.168.111.5"],"ingressVIPs":["192.168.111.4"],"subnetUUIDs":["a2e46975-2cde-4a49-9dda-815eb4fcd681"]}}}'
-  creationTimestamp: null
   name: ostest
 spec:
   apiVIPs: