Add CEL test for `ObservabilityPolicy` CRD

[shaun-nx]

Overview

As a user of NGF, I would like to add CEL tests for the ObservabilityPolicy CRD so that I can be confident that the CEL validation works as I expect

UACs

• Add test for the targetRef CEL validation
• Add test for the tracing CEL validation

targetRef validation:

x-kubernetes-validations:
    - message: 'TargetRef Kind must be: HTTPRoute or GRPCRoute'
      rule: (self.exists(t, t.kind=='HTTPRoute') || self.exists(t, t.kind=='GRPCRoute'))
    - message: TargetRef Group must be gateway.networking.k8s.io
      rule: self.all(t, t.group=='gateway.networking.k8s.io')
    - message: TargetRef Kind and Name combination must be unique
      rule: self.all(p1, self.exists_one(p2, (p1.name == p2.name) && (p1.kind
        == p2.kind)))

tracing validation:

x-kubernetes-validations:
    - message: ratio can only be specified if strategy is of type ratio
      rule: '!(has(self.ratio) && self.strategy != ''ratio'')'

[nginx-bot]

Hi @shaun-nx! Welcome to the project! 🎉

Thanks for opening this issue!
Be sure to check out our Contributing Guidelines and the Issue Lifecycle while you wait for someone on the team to take a look at this.