Use graceful shutdown for workers

[sbernauer]

Description

Fixes #429

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

# Author
- [x] Changes are OpenShift compatible
- [ ] CRD changes approved - PENDING
- [x] Helm chart can be installed and deployed operator works
- [x] Integration tests passed (for non trivial changes) https://ci.stackable.tech/job/trino-operator-it-custom/95/

# Reviewer
- [x] Code contains useful comments
- [x] (Integration-)Test cases added
- [x] Documentation added or updated
- [x] Changelog updated
- [x] Cargo.toml only contains references to git tags (not specific commits or branches)

# Acceptance
- [ ] Feature Tracker has been updated
- [ ] Proper release label has been added

[maltesander]

Just spelling. Maybe we should include our 24h default certificate rotation that kills everything anyways :)?

[sbernauer]

@maltesander ready for another round of review

[sbernauer]

Started https://ci.stackable.tech/view/02%20Operator%20Tests%20(custom)/job/trino-operator-it-custom/95/

[maltesander]

Minor things. LGTM otherwise if operator-rs is released!

[maltesander]

LGTM.