GH-51232: [CI] Remove the "take" comment bot for self-assigning issues

[thisisnic]

Rationale for this change

Anyone could assign themselves an issue by commenting "take", including issues already assigned to someone else. Assignment should be handled by committers and collaborators instead.

What changes are included in this PR?

Removes the issue_assign job from the comment bot workflow and updates the contributor docs to say that a committer or collaborator will assign issues on request.

Are these changes tested?

No. Docs were checked with sphinx-lint via pre-commit.

Are there any user-facing changes?

No. Contributors can no longer self-assign issues by commenting "take".

• GitHub Issue: [CI] Update comment bot to remove "take" command #51232

[Copilot]

🟡 Changes recommended

The workflow still runs on PR comments (issue_comment applies to PRs too), so take can unintentionally assign pull requests unless the job is additionally gated to issues-only.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Updates Arrow’s GitHub comment bot (“take”) behavior and contributor docs so that self-assignment only occurs when an issue is currently unassigned, preventing accidental reassignment of already-owned issues.

Changes:

• Restrict the comment_bot.yml “Assign issue” job to run only when the issue has no assignee.
• Update developer documentation to clarify that take only works on unassigned issues.

File summaries

File	Description
docs/source/developers/bug_reports.rst	Clarifies that take only self-assigns unassigned issues.
CONTRIBUTING.md	Updates contributor guidance to match the new take behavior.
.github/workflows/comment_bot.yml	Adds an “unassigned only” guard to the take-based assignment job.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Lite

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[Copilot]

🟢 Approval recommended

The workflow condition change directly addresses the reported issue and the accompanying documentation updates are consistent with the new behavior.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 0 new
• Review effort level: Lite

[Copilot]

🔵 Needs a closer look

Reconcile the implementation and PR description, and update the inconsistent assignment guidance.

Review details

Suppressed comments (2)

docs/source/developers/guide/tutorials/python_tutorial.rst:95

• This new assignment policy leaves the R tutorial inconsistent: docs/source/developers/guide/tutorials/r_tutorial.rst:92 still tells contributors an issue is “assigned to yourself”, which is no longer possible for non-collaborators after removing take. Please update that tutorial in the same PR.

We should make sure to let others know we are working on the issue.
You can do that by adding a comment to the issue created saying you
would like to work on it, and a committer or collaborator will assign
it to you.

docs/source/developers/guide/tutorials/python_tutorial.rst:95

• The workflow change removes the take command entirely, while the PR description says take should still assign an unassigned issue. This also changes the contributor-facing behavior documented here; please reconcile the implementation and PR description (the linked issue explicitly requests removing the command).

We should make sure to let others know we are working on the issue.
You can do that by adding a comment to the issue created saying you
would like to work on it, and a committer or collaborator will assign
it to you.

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Lite

[rok]

LGTM.