Improve securityContext for operator Deployment

[mjura]

1. Restrict container from acquiring additional privileges (securityContext.allowPrivilegeEscalation)
2. Mount container's root filesystem as read only (securityContext.readOnlyRootFilesystem)
3. Ensure that container won't be started as privileged container (securityContext.privileged)

Issue: #591

What this PR does / why we need it:

Which issue(s) this PR fixes
Issue #

Special notes for your reviewer:

Checklist:

• squashed commits into logical changes
• includes documentation
• adds unit tests
• adds or updates e2e tests
• backport needed

[yiannistri]

I believe these settings should be under .spec.template.spec.containers[n].securityContext rather than spec.template.spec.securityContext. See https://kubernetes.io/docs/tasks/configure-pod-container/security-context/#set-the-security-context-for-a-pod and https://kubernetes.io/docs/tasks/configure-pod-container/security-context/

[mjura]

I believe these settings should be under .spec.template.spec.containers[n].securityContext rather than spec.template.spec.securityContext. See https://kubernetes.io/docs/tasks/configure-pod-container/security-context/#set-the-security-context-for-a-pod and https://kubernetes.io/docs/tasks/configure-pod-container/security-context/

you are right, I discovered it after testing. thank you for pointing this

[yiannistri]

🛡️ 👌