Setting busybox repository and tag via values.yaml

[FathomlessFunction]

What was changed

I've updated the helmchart such that the busybox repository and tag are set via values set in values.yaml

Why?

When working in isolated networks, having this image always set to busybox:latest as it is currently will cause the cluster to always try and check for what the latest version is, causing an ImagePullBackoff error.
Similarly, I've needed to pull this image from a custom registry rather than the public one, too, so having the public repo hard-coded is inconvenient.

It's easy enough to patch yourself, but I thought other users in similar situations would appreciate not needing to do so.

If values.yaml needs to be backwards compatible, please let me know and I'd be happy to work out how to make this set the image to busybox:latest if there is no definition for Values.busybox!

Checklist

1. Closes N/A

2. How was this tested:
   I ran the cluster locally using values.yaml and checked that all pods were healthy.

3. Any docs updates needed?
   I don't believe so, but please correct me if I am wrong!

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