BE: ARM Fix: Update base image sha

[junaid-ali]

fixes: #1440

• Breaking change? (if so, please describe the impact and migration path for existing application instances)

What changes did you make? (Give an overview)
Copied the index digest from: https://hub.docker.com/layers/azul/zulu-openjdk-alpine/21.0.8-jre-headless/images, so it should now correctly work on both amd64 and arm64 machines

Is there anything you'd like reviewers to focus on?

How Has This Been Tested? (put an "x" (case-sensitive!) next to an item)

• No need to
• Manually (please, describe, if necessary)
  Manually pulled the digest and ran it on both an amd64 and an arm64 (graviton) machine

## ------------------ arm64

$ tag=sha256:48356cf1b81243b6e236509bb6ae281969fc0eade03f622220973a4e224cd768
$ uname -i
aarch64
$ ctr i pull docker.io/azul/zulu-openjdk-alpine:21.0.8-jre-headless@$tag
...
unpacking linux/arm64/v8 sha256:48356cf1b81243b6e236509bb6ae281969fc0eade03f622220973a4e224cd768...
done: 7.351239ms

$ crictl inspecti docker.io/azul/zulu-openjdk-alpine:21.0.8-jre-headless@$tag | jq -r .info.imageSpec.architecture
arm64

$ ctr run --rm -t docker.io/azul/zulu-openjdk-alpine:21.0.8-jre-headless@$tag test ash
/ #


## ------------------ amd64

$ tag=sha256:48356cf1b81243b6e236509bb6ae281969fc0eade03f622220973a4e224cd768
$ uname -i
x86_64
$ ctr i pull docker.io/azul/zulu-openjdk-alpine:21.0.8-jre-headless@$tag
...
unpacking linux/amd64 sha256:48356cf1b81243b6e236509bb6ae281969fc0eade03f622220973a4e224cd768...
done: 8.933226ms

$ crictl inspecti docker.io/azul/zulu-openjdk-alpine:21.0.8-jre-headless@$tag | jq -r .info.imageSpec.architecture
amd64

$ ctr run --rm -t docker.io/azul/zulu-openjdk-alpine:21.0.8-jre-headless@$tag test ash
/ #

• Unit checks
• Integration checks
• Covered by existing automation

Checklist (put an "x" (case-sensitive!) next to all the items, otherwise the build will fail)

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (e.g. ENVIRONMENT VARIABLES)
• My changes generate no new warnings (e.g. Sonar is happy)
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged

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[junaid-ali]

I think we should ideally have some tests as well so that it won't break in future.

[github-actions]

Hi junaid-ali! 👋

Welcome, and thank you for opening your first PR in the repo!

Please wait for triaging by our maintainers.

Please take a look at our contributing guide.

[Haarolean]

I think we should ideally have some tests as well so that it won't break in future.

yeah, see #560

[junaid-ali]

Thanks @Haarolean for the review and approval.