fix(kubernetes): Fix CKV_K8S_31 for CronJobs

[tsmithv11]

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Description

Fixes CronJob check for SeccompProfile under spec instead of metadata

Fixes #2222

Checklist:

• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] I have added tests that prove my feature, policy, or fix is effective and works
• [x] New and existing tests pass locally with my changes