refactor: Change graceful shutdown timeout to string

[sbernauer]

Description

Part of #461
As discussed in Arc meeting on 2023-08-23

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
- [x] CRD changes approved
- [x] Helm chart can be installed and deployed operator works
- [ ] Integration tests passed (for non trivial changes)

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

# Acceptance
- [x] Proper release label has been added

[maltesander]

LGTM!

[lfrancke]

This changes the CRD? Do we need anything in the docs, release notes etc.?

[lfrancke]

ping @maltesander in the absence of @sbernauer

[maltesander]

Yes it changes the CRD slightly.
graceful_shutdown_seconds was renamed to graceful_shutdown_timeout and takes a duration (string like 1m) instead of an integer of seconds.
This was not released yet as far as i remember and is just another optional field added. So no breaking changes i would say.
But i think its not reflected in the docs https://github.com/stackabletech/trino-operator/blob/main/docs/modules/trino/pages/usage_guide/operations/graceful-shutdown.adoc properly.

[lfrancke]

Can you link the PR where you fixed the docs?

[maltesander]

Sure thing! #466