Refactor FXIOS-14031 [Danger] Danger rule with dispatch legacy

[lmarceau]

📜 Tickets

Jira ticket
Github issue

💡 Description

Add check so we fail if new dispatchLegacy are introduced in the codebase

📝 Checklist

• I filled in the ticket numbers and a description of my work
• I updated the PR name to follow our PR naming guidelines
• I ensured unit tests pass and wrote tests for new code
• If working on UI, I checked and implemented accessibility (Dynamic Text and VoiceOver)
• If adding telemetry, I read the data stewardship requirements and will request a data review
• If adding or modifying strings, I read the guidelines and will request a string review from l10n
• If needed, I updated documentation and added comments to complex code

[mobiletest-ci-bot]

🧹 Tidy commit

Just 1 file(s) touched. Thanks for keeping it clean and review-friendly!

❌ Per-file test coverage gate

The following changed file(s) are below 35.0% coverage:

File	Coverage	Required
Dangerfile.swift	0.0%	35.0%

Generated by 🚫 Danger Swift against 72c59b2