refactor(parquet): remove unused page_state_s fields

[vyasr]

Description

As a first step to simplifying usage of the page_state_s struct in the various Parquet kernels, this PR eliminates a handful of dead fields (lvl_start, lvl_end, first_output_value) that were previously unused. I didn't trace the history but I presume the usage of these fields was removed by a prior refactor.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: a59ab700-c83f-46f1-8170-310eec9e4d1b

📥 Commits

Reviewing files that changed from the base of the PR and between 982a387 and 9c959de.

📒 Files selected for processing (1)

• cpp/src/io/parquet/page_decode.cuh

---

📝 Walkthrough

Summary by CodeRabbit

• Refactor
  • Simplified internal Parquet page decoding state management.
  • Removed redundant level-tracking data while preserving existing level parsing and processing behavior.

Walkthrough

Parquet page decoding removes obsolete level-tracking fields from page_state_s. Level initialization and local page setup now rely on absolute level bounds without storing per-section starts, ends, or the first output value.

Changes

Parquet page decoding

Layer / File(s)	Summary
Remove obsolete page state cpp/src/io/parquet/page_decode.cuh	page_state_s no longer stores level start/end pointers or first_output_value.
Use absolute level bounds cpp/src/io/parquet/page_decode.cuh	InitLevelSection and setup_local_page_info stop writing removed fields while preserving absolute level bounds and data-start progression.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested labels: cuIO

Suggested reviewers: rjzamora, bdice

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: removing unused fields from page_state_s in Parquet code.
Description check	✅ Passed	The description is clearly related to the patch and matches the removed page_state_s fields.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands.}

[vyasr]

/merge