fix(helm): implement ordered cleanup for Helm releases based on dependency levels

[BabisK]

Fixes: #9837
Related: #7284
Merge before/after: Dependent or prerequisite PRs

Description

Respect the dependency graph between helm releases during clean up. Levels of the graph are cleaned on reverse order compared to installation. Releases in the same level are cleaned up in reverse order too.

User facing changes (remove if N/A)

Before
Releases are undeployed in the order they are mentioned in Config.

^CCleaning up...
release "postgres-operator" uninstalled
release "postgres" uninstalled

After
Releases are undeployed in the reverse order they were deployed, respecting the dependsOn values.

^CCleaning up...
release "postgres" uninstalled
release "postgres-operator" uninstalled

[gemini-code-assist]

Summary of Changes

Hello @BabisK, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a critical issue in Helm release cleanup by introducing a dependency-aware uninstallation process. Previously, releases were cleaned up in an arbitrary order, which could lead to errors if a dependent release was removed before its dependencies. The changes ensure that Helm releases are now uninstalled in the reverse order of their deployment, respecting defined dependencies, thereby providing a more robust and reliable cleanup mechanism.

Highlights

• Helm Cleanup Logic: The core Helm cleanup function (Cleanup) has been refactored to first construct a dependency graph of all configured Helm releases.
• Ordered Uninstallation: Releases are now uninstalled level by level, starting from the highest dependency level (most dependent releases) down to the lowest (least dependent releases). Within each level, releases are also uninstalled in reverse order of their definition, ensuring that dependencies are respected during teardown.
• Go slices Package Adoption: The new slices package (Go 1.21+) is utilized to facilitate backward iteration over release levels and releases within each level, ensuring the correct cleanup order.
• Improved Testing: A new comprehensive test case has been added to helm_test.go to explicitly validate the new ordered cleanup behavior, ensuring that releases are deleted in the correct sequence based on their dependencies.

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[gemini-code-assist]

Code Review

This pull request introduces an important fix for Helm release cleanup, ensuring that dependencies are respected by deleting releases in the reverse order of their deployment. The implementation correctly uses a dependency graph to determine the cleanup order, handling different dependency levels and the order of releases within each level. I've added comments to improve error handling and logging.