feat: add extraContainers and extraInitContainers to Hydra Janitor

[supercairos]

Related Issue or Design Document

Checklist

• I have read the contributing guidelines and signed the CLA.
• I have referenced an issue containing the design document if my change introduces a new feature.
• I have read the security policy.
• I confirm that this pull request does not address a security vulnerability.
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• I have added tests that prove my fix is effective or that my feature works.
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Further comments

[supercairos]

@Demonsthere can you review this ?

[Demonsthere]

LGTM :)