Fix detector_rules diff suppression for order mismatches (#2509)

[sakazuki]

Summary

Fixes an issue where changes to the detector_rules block in Cloud Guard Detector Recipe resources would trigger spurious diffs whenever the API response order differs from the HCL configuration block order.

Problem

• The OCI Cloud Guard API returns all detector rules (including default rules copied from the source recipe) in an unpredictable order
• When the order of API response differs from the order of blocks defined in HCL, Terraform would report a diff even though no actual changes were made
• This caused unnecessary plan failures and confusion for users

Solution

1. Filtered rule set: Modified SetData() to only include rules that were explicitly defined in the HCL configuration, preventing spurious diffs caused by API-injected default rules
2. Deterministic ordering: All rules are now sorted alphabetically by detector_rule_id for consistent state
3. Smart diff suppression: Added a DiffSuppressFunc that intelligently compares rules by detector_rule_id rather than list index, preventing false positives when HCL blocks are reordered
4. Helper functions: Added utility functions to:
   • Extract configured rule IDs from HCL
   • Filter rules by ID set
   • Sort rules consistently

Files Changed

• cloud_guard_detector_recipe_resource.go

Testing

• The fix leverages Terraform's schema validation and diff suppression mechanisms
• No behavioral changes to the API or resource output
• All detector rules (including defaults) remain available via the effective_detector_rules attribute for reference

Related Issue

Fixes #2509

[tf-oci-pub]

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