CCO Pod crashes on BM cluster when AWS Root Credential exists

Description of problem:

Similar to https://bugzilla.redhat.com/show_bug.cgi?id=1996624, when the AWS root credential (must possesses the "iam:SimulatePrincipalPolicy" permission) exists on a BM cluster, the CCO Pod crashes when running the secretannotator controller. 

Steps to Reproduce:

1. Install a BM cluster
fxie-mac:cloud-credential-operator fxie$ oc get infrastructures.config.openshift.io cluster -o yaml
apiVersion: config.openshift.io/v1
kind: Infrastructure
metadata:
  creationTimestamp: "2024-01-28T19:50:05Z"
  generation: 1
  name: cluster
  resourceVersion: "510"
  uid: 45bc2a29-032b-4c74-8967-83c73b0141c4
spec:
  cloudConfig:
    name: ""
  platformSpec:
    type: None
status:
  apiServerInternalURI: https://api-int.fxie-bm1.qe.devcluster.openshift.com:6443
  apiServerURL: https://api.fxie-bm1.qe.devcluster.openshift.com:6443
  controlPlaneTopology: SingleReplica
  cpuPartitioning: None
  etcdDiscoveryDomain: ""
  infrastructureName: fxie-bm1-x74wn
  infrastructureTopology: SingleReplica
  platform: None
  platformStatus:
    type: None 

2. Create an AWS user with IAMReadOnlyAccess permissions:
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "iam:GenerateCredentialReport",
                "iam:GenerateServiceLastAccessedDetails",
                "iam:Get*",
                "iam:List*",
                "iam:SimulateCustomPolicy",
                "iam:SimulatePrincipalPolicy"
            ],
            "Resource": "*"
        }
    ]
}

3. Create AWS root credentials with a set of access keys of the user above
4. Trigger a reconcile of the secretannotator controller, e.g. via editting cloudcredential/cluster     

Logs:

time="2024-01-29T04:47:27Z" level=warning msg="Action not allowed with tested creds" action="iam:CreateAccessKey" controller=secretannotator
time="2024-01-29T04:47:27Z" level=warning msg="Action not allowed with tested creds" action="iam:CreateUser" controller=secretannotator
time="2024-01-29T04:47:27Z" level=warning msg="Action not allowed with tested creds" action="iam:DeleteAccessKey" controller=secretannotator
time="2024-01-29T04:47:27Z" level=warning msg="Action not allowed with tested creds" action="iam:DeleteUser" controller=secretannotator
time="2024-01-29T04:47:27Z" level=warning msg="Action not allowed with tested creds" action="iam:DeleteUserPolicy" controller=secretannotator
time="2024-01-29T04:47:27Z" level=warning msg="Action not allowed with tested creds" action="iam:PutUserPolicy" controller=secretannotator
time="2024-01-29T04:47:27Z" level=warning msg="Action not allowed with tested creds" action="iam:TagUser" controller=secretannotator
time="2024-01-29T04:47:27Z" level=warning msg="Tested creds not able to perform all requested actions" controller=secretannotator
I0129 04:47:27.988535       1 reflector.go:289] Starting reflector *v1.Infrastructure (10h37m20.569091933s) from sigs.k8s.io/controller-runtime/pkg/cache/internal/informers.go:233
I0129 04:47:27.988546       1 reflector.go:325] Listing and watching *v1.Infrastructure from sigs.k8s.io/controller-runtime/pkg/cache/internal/informers.go:233
I0129 04:47:27.989503       1 reflector.go:351] Caches populated for *v1.Infrastructure from sigs.k8s.io/controller-runtime/pkg/cache/internal/informers.go:233
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1a964a0]
 
goroutine 341 [running]:
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile.func1()
/go/src/github.com/openshift/cloud-credential-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:115 +0x1e5
panic({0x3fe72a0?, 0x809b9e0?})
/usr/lib/golang/src/runtime/panic.go:914 +0x21f
github.com/openshift/cloud-credential-operator/pkg/operator/utils/aws.LoadInfrastructureRegion({0x562e1c0?, 0xc002c99a70?}, {0x5639ef0, 0xc0001b6690})
/go/src/github.com/openshift/cloud-credential-operator/pkg/operator/utils/aws/utils.go:72 +0x40
github.com/openshift/cloud-credential-operator/pkg/operator/secretannotator/aws.(*ReconcileCloudCredSecret).validateCloudCredsSecret(0xc0008c2000, 0xc002586000)
/go/src/github.com/openshift/cloud-credential-operator/pkg/operator/secretannotator/aws/reconciler.go:206 +0x1a5
github.com/openshift/cloud-credential-operator/pkg/operator/secretannotator/aws.(*ReconcileCloudCredSecret).Reconcile(0xc0008c2000, {0x30?, 0xc000680c00?}, {0x4f38a3d?, 0x0?}, {0x4f33a20?, 0x416325?})
/go/src/github.com/openshift/cloud-credential-operator/pkg/operator/secretannotator/aws/reconciler.go:166 +0x605
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile(0x561ff20?, {0x561ff20?, 0xc002ff3b00?}, {0x4f38a3d?, 0x3b180c0?}, {0x4f33a20?, 0x55eea08?})
/go/src/github.com/openshift/cloud-credential-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:118 +0xb7
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler(0xc000189360, {0x561ff58, 0xc0007e5040}, {0x4589f00?, 0xc000570b40?})
/go/src/github.com/openshift/cloud-credential-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:314 +0x365
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem(0xc000189360, {0x561ff58, 0xc0007e5040})
/go/src/github.com/openshift/cloud-credential-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:265 +0x1c9
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2()
/go/src/github.com/openshift/cloud-credential-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:226 +0x79
created by sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2 in goroutine 183
/go/src/github.com/openshift/cloud-credential-operator/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:222 +0x565

Actual results:

CCO Pod crashes and restarts in a loop:
fxie-mac:cloud-credential-operator fxie$ oc get po -n openshift-cloud-credential-operator -w
NAME                                         READY   STATUS    RESTARTS        AGE
cloud-credential-operator-657bdffdff-9wzrs   2/2     Running   3 (2m35s ago)   8h