Run test utility containers with tini

[nightkr]

Description

This should help speed up test teardown, since they handle SIGTERM instead of having to wait for the container shutdown to timeout.

Definition of Done Checklist

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1. Integration tests passed (for non trivial changes)

Reviewer

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1. Code contains useful comments
2. Code contains useful logging statements
3. (Integration-)Test cases added
4. Documentation added or updated. Follows the style guide.
5. Changelog updated
6. Cargo.toml only contains references to git tags (not specific commits or branches)

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1. Feature Tracker has been updated
2. Proper release label has been added
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[razvan]

I don't see where tini is used.

[nightkr]

It's managed by the shareProcessNamespace flag.