CI: clean untracked files when an error occurred

[pyby]

Description

When Xcode 15 pushed a build phases reorder (#374) to have the custom icons, a risk reappeared again to not have a clean repository during a build issue.

The issue came again because of a tvOS build issue: https://github.com/SRGSSR/playsrg-apple/deployments/playsrg-tvos-nightly%2BPLAYRTS-5527-swimlane-link-to-micropage

The copied original application icons are not removed:

16:25:53   Uncommitted changes:
16:25:53   ?? OriginalAppIcon.appiconset/
16:25:53   ?? OriginalAppStoreTVIcon.appiconset/
16:25:53   ?? OriginalTVAppIcon.appiconset/

This PR proposes to force a full clean if an error occurred, including cache and untracked files like the last-#{service}#{platform}nightlies-success-git-commit-hash.txt files.

Changes Made

• Update Fastfile error handles, to not skip git clean during the reset step.

Checklist

• I have followed the project's style guidelines.
• I have performed a self-review of my own changes.
• I have made corresponding changes to the documentation.
• My changes do not generate new warnings.
• I have tested my changes and I am confident that it works as expected and doesn't introduce any known regressions.
• I have reviewed the contribution guidelines.