[Sample] disallow-privilege-escalation: Simplify CEL expressions using optional

[epasham]

Problem Statement

Simplify the CEL expression using optional. Update the CEL expression and test and validate disallow-privilege-escalation policy

Solution Description

The policy has redundant CEL expressions and needs to be simplified. containers, initcontainers and ephemeral containers needs to be captured in a variable and use the variable in CEL expression

Example "Good" Resource

No response

Example "Bad" Resource

No response

Other Comments

No response

Slack discussion

No response

Troubleshooting

• [X] I have read and followed the documentation AND the troubleshooting guide.
• [X] I have verified the policy does not exist in the samples library.

[epasham]

/assign @epasham