Remove output-format=text setting

[MichaReiser]

Summary

Using output-format=text is a hard error since Ruff 0.5 (#12010).

This PR removes the custom error message.

Test Plan

ruff failed
  Cause: Failed to parse /home/micha/astral/test/pyproject.toml
  Cause: TOML parse error at line 4, column 15
  |
4 | output-format="text"
  |               ^^^^^^
unknown variant `text`, expected one of `concise`, `full`, `json`, `json-lines`, `junit`, `grouped`, `github`, `gitlab`, `pylint`, `rdjson`, `azure`, `sarif`

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[AlexWaygood]

Same thoughts as #12833 (review) -- I'd probably keep the nice error message for another minor version personally, but don't have a strong opinion

[AlexWaygood]

Thanks!