fix(chart): Helm uninstall with deleting webhooks

[kaiiyvwu]

Description

add delete mutatingwebhookconfigurations and validatingwebhookconfigurations command in post-delete-job

Related Issues

Fixes #751

Checklist

Note: Ensure your PR title follows the Conventional Commits format (e.g., feat(scheduler): add new feature)

• Self-reviewed
• Added/updated tests (if needed)
• Updated documentation (if needed)

Breaking Changes

Additional Notes

[SiorMeir]

Hey @kaiiyvwu, thank you for the contribution!

This is a really important improvement and is much appreciated.

Couple of notes regarding the PR:

1. We can maybe achieve a cleaner and more correct cleanup of KAI-scheduler by delete kaiConfig singleton instead, as all objects point to it via ownerReference. This should trigger a cascading deletion of all KAI's resources.

2. We've implemented a changelog update requirement so all important updates to kai-scheduler, so please update CHANGELOG.md in your PR. you can see examples for this our last merged PRs (here's one)

I'll add backport labels as well for versions v0.10 and v0.12 so we can implement this in LTS versions