OperatorConfig CEL Validation

[bernot-dev]

Adds kubebuilder CEL validations to OperatorConfig fields based on the migration away from webhook validation.

• Validates prometheus label keys in externalLabels
• Validates queryProjectID constraints (length and regex pattern)
• Adds isURL checks for generatorUrl, exports.url, externalURL
• Implements RFC 1123 label constraints for AlertmanagerEndpoints namespace and name
• Validates TLSConfig KeySecret name
• Enforces HTTP/HTTPS scheme for AlertmanagerEndpoints

[gemini-code-assist]

Code Review

This pull request introduces various OpenAPI and CEL validation constraints to the OperatorConfig CRD definitions and adds corresponding end-to-end validation tests. The reviewer identified several critical issues: the use of the non-existent CEL function isURL which will cause CRD application failures, and a MinLength constraint on queryProjectID that incorrectly prevents it from being left blank. Additionally, the reviewer noted a duplicate import of k8s.io/api/core/v1 under different aliases in the test file, recommending the consistent use of the existing v1 alias.

[bernot-dev]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces declarative CEL validations and kubebuilder constraints to OperatorConfig CRD fields, ensuring stricter validation for URLs, GCP project IDs, external labels, and secret names directly at the API level. Corresponding end-to-end tests were updated to clean up test resources and verify these new validation rules. The review feedback suggests further strengthening the validations by enforcing mutual exclusivity between the secret and configMap fields in SecretOrConfigMap, as well as adding DNS subdomain validation for the configMap name.