Operator crashes when using Static Containers with securityContext.readOnlyRootFilesystem=`true`

[bitfisher]

What did you do to encounter the bug?
Install operator with helm upgrade mongodb-operator mongodb/mongodb-kubernetes --namespace mongodb-operator --install --create-namespace --reset-values --set operator.mdbDefaultArchitecture="static"

What did you expect?
Operator running

What happened instead?
Operator is crashing with error {"level":"error","caller":"mongodb-kubernetes/main.go:475","msg":"could not set up webhook: mkdir /tmp/k8s-webhook-server: read-only file system","stacktrace":"main.setupWebhook\n\t/go/src/github.com/mongodb/mongodb-kubernetes/main.go:475\nmain.main\n\t/go/src/github.com/mongodb/mongodb-kubernetes/main.go:192\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:283"}

Operator Information

• Operator Version: 1.4.0
• MongoDB Image used: quay.io/mongodb/mongodb-kubernetes:1.4.0

Workaround
Patch deployment with

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-kubernetes-operator
  namespace: mongodb-operator
spec:
  template:
    spec:
      securityContext:
        runAsNonRoot: true
        runAsUser: 2000
        runAsGroup: 2000
        fsGroup: 2000
        fsGroupChangePolicy: "OnRootMismatch"
        seccompProfile:
          type: "RuntimeDefault"
      volumes:
      - name: tmp
        emptyDir:
          medium: Memory
      containers:
        - name: mongodb-kubernetes-operator
          securityContext:
            privileged: false
            allowPrivilegeEscalation: false
            readOnlyRootFilesystem: true
            capabilities:
              drop:
              - ALL
          volumeMounts:
          - name: tmp
            mountPath: /tmp