PR Summary

Closes #356

• Removes anomaly and climatology, which have had deprecation warnings since v2023.02.0
• Also removes _find_time_invariant_vars and _setup_clim_anom_input from internal API, which were exclusively used in anomaly and climatology

PR Checklist

General

• Link the issue this PR resolves by adding closes #XXX to the PR description where XXX is the number of the issue.
• Add a brief summary of changes to docs/release-notes.rst
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