fix: resolve leftover conflict marker in bria pipeline docstring

[PlagueKind]

What does this PR do?

Fixes a leftover merge conflict marker in the guidance_scale docstring of pipelines/bria/pipeline_bria.py. Kept the huggingface.co/papers URLs over the arxiv.org ones, consistent with the rest of the codebase.

Before submitting

• Did you use an AI agent (Claude Code, Codex, Cursor, etc.) to help with this PR? If so:
  • Did you read the Coding with AI agents guide?
  • Did you self-review the diff against .ai/review-rules.md?
• Did you read the contributor guideline?
• Did you read our philosophy doc?
• Was this discussed/approved via a GitHub issue or the forum?
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?
• Are you the author (or part of the team) of the model/pipeline?

[github-actions]

Hi @PlagueKind, thanks for the PR! It does not appear to link an issue it fixes. If this PR addresses an existing issue, please add a closing keyword (e.g. Fixes #1234) to the PR description so the issue is linked. See the contribution guide for more details. If this PR intentionally does not fix a tracked issue, a maintainer can add the no-issue-needed label to silence this reminder.