fix: Template image for Helm Cleanup job due to bitnami updates

[DaThumpingRabbit]

What type of PR is this?
/kind hotfix

What this PR does / Why we need it:
Following this update bitnami/charts#35164, it will not be possible to keep using the kubectl image from bitnami for all users
This PR allows to choose what image to use to run the post-delete cleanup job and default on the best alternative I could find at the moment rancher/kubectl

Special notes for your reviewer:
Please let me know if bitnami should stay the default registry based on your guidelines

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[markmandel]

🤔 seems like a reasonable change - just wondering why we want to make it configurable? Might as well just switch to the rancher version and call it a day.

Just a question of ongoign maintenance and documentation.

[markmandel]

Just noted, there is an official kubectl image: https://www.reddit.com/r/kubernetes/s/1rDLvH7rtR

We provide an official kubectl image these days:
registry.k8s.io/kubectl:v1.33.3

Fair warning for production dependency on this host: https://registry.k8s.io#stability

TLDR this is volunteer operated and you're not paying us for an SLA. Mirror if you need uptime guaranteed, docs provided for doing that.

Also, kubectl is a single static go binary, so making an image for it is pretty trivial.

[DaThumpingRabbit]

Just noted, there is an official kubectl image: https://www.reddit.com/r/kubernetes/s/1rDLvH7rtR

I saw the image you mentioned but was a bit afraid about the stability warning
I have never used it so I don't know if it will be safe enough

🤔 seems like a reasonable change - just wondering why we want to make it configurable? Might as well just switch to the rancher version and call it a day.

Just a question of ongoign maintenance and documentation.

About this, I thought that maybe if some customers are paying the new bitnami secure package, they might want to switch back to bitnami
However if that makes more sense for you to just switch it, I am fine with that as well

[DaThumpingRabbit]

@markmandel I have just made some tests and I don't think that this new image will be a good fit anyway since it does not come with a shell and won't work in that scenario

Only alternative to bitnami I found for now that comes with a shell is alpine/k8s
It has way more things than is needed but did not find a better option for now

Please let me know if this would be a good alternative for this