Fix bug in transect operator

[jwarner8]

Fixes a bug in the transect operator where the minimum grid spacing could become negative. Fixes a bug in the meta-data where too many triggers are used (thanks @daflack for spotting this). Fixes missing entries in the rose-suite.conf.example file for the transect.

Contribution checklist

Aim to have all relevant checks ticked off before merging. See the developer's guide for more detail.

• [x] Documentation has been updated to reflect change.
• [x] New code has tests, and affected old tests have been updated.
• [x] All tests and CI checks pass.
• [x] Ensured the pull request title is descriptive.
• [ ] Conda lock files have been updated if dependencies have changed.
• [ ] Attributed any Generative AI, such as GitHub Copilot, used in this PR.
• [x] Marked the PR as ready to review.

[github-actions[bot]]

[jfrost-mo]

Go ahead and merge.