ci: run autofix before main CI on pull requests

[ojasarora77]

Fixes #38291

Summary

Runs autofix.ci as the first job in main-ci.yml for pull requests, so downstream tests and style checks run against autofixed code instead of racing with a separate autofix workflow.

• Add a run-autofix job to main-ci.yml that calls autofix.yml via workflow_call
• Gate pre_job (and the rest of the pipeline) on autofix completing
• Remove the standalone pull_request trigger from autofix.yml to prevent parallel runs
• Keep push and merge_group triggers on autofix.yml unchanged

This uses a reusable workflow call rather than workflow_run so child workflows continue to check out the PR head normally without extra ref plumbing.

From Cursor

Test plan

• Open a PR with a deliberate ruff formatting issue and confirm autofix runs before API/Web tests
• Confirm merge group and push-to-main CI still run without waiting on autofix
• Confirm a PR that needs no autofix changes still completes the full pipeline after the autofix job