chore(ci): don't generate files on commits generated by the generate workflow

[nirinchev]

Description

This attempts to break the cycle of generated file updates by skipping the Update automatically generated files job if it's run on a commit that was created by the same workflow.

This attempts to redo #6546.

Checklist

• New tests and/or benchmarks are included
• Documentation is changed or added
• I have signed the MongoDB Contributor License Agreement (https://www.mongodb.com/legal/contributor-agreement)

Motivation and Context

• Bugfix
• New feature
• Dependency update
• Misc

Open Questions

Dependents

Types of changes

• Backport Needed
• Patch (non-breaking change which fixes an issue)
• Minor (non-breaking change which adds functionality)
• Major (fix or feature that would cause existing functionality to change)